Absolutely not. Nope nope nope.

It's one thing to live with that situation as an adult, but you have a daughter and another on the way and that changes everything.  You need to look out for your children first and foremost and ensure their safety. You're their mother and literally there to protect them until they are fully functional independent adults.

where is SS mother? Why does she not have more time with him?  It is not your responsibility to make her become the mother that you need to be for your own children.  Look out for yourself and your little ones.

Especially after you deliver, your body will go in to full on mother protective zone that absolutely no one should get in the way of. I'm so sorry you have to deal what that.

File an RO/PO keeping him away from you and your young ones.  His behavior at school may be enough to get a judge to approve the order. Take it out of your DH's hands and protect your girls.  Or your girl and your pending TBD as the case may be.  Congratulations on the STB LO.

IMHO of course.

Would you want a 13 year old teenager (being diagnosed with autism) living with you full time if he has had numerous outbursts of being violent (in social disagreements as he struggles to regulate emotion or sometimes instigated by himself) and ignoring female boundaries at school (putting his hands on females even though he had been asked not to) his excuse being he didn't think anything would come of it? 
 

HELL Naw!!!!!

He needs to be in an institution or boarding school that specializes in behavioral issues ....

Yeah, drop a teen boy with emotional and behavioral problems on the doorstep of a pregnant woman with a toddler. That should go really well. You are sane and also, though, the pregnancy hormones have you feeling extra protective of your baby and toddler. And that's not a bad thing.

His BM "just can't handle him." Well tough shit, neither can you. But you didn't birth him, she did. I would focus my energies on first protecting your health and your little ones, and second getting this Cowbird to woman up and take care if the child she created. Any possible way this can be forced should be pursued. If she's not incarcerated or declared unfit, she needs to take him. Fk "can't handle him." He's not a baby, he's a teen with what sounds like very mild autism. This is my first recommendation and my second is back to boarding school. Your DH needs to find the money. If he can't and BM actually meets the definition of unfit, every second he is in your home he needs to be watched by your DH. 

I think it's normal, particularly during pregnancy, to worry about every possible way your children could be hurt. So I don't think you're insane.

However, I do think it's unreasonable for you to expect your husband to choose you/your children over his son, especially taking into consideration that the BM is completely worthless and won't take responsibility for the child either. Of course he is going to exhaust every avenue possible to keep SS in his home. What, exactly, is the alternative? Is a decent boarding school an option for y'all? One that is equipped and capable of guiding SS to becoming an independent adult and not just a place that will keep him locked away? Surrender him to the care of the state? I'm just not sure what else could be done with regard to your living situation, from your husband's perspective. It would be a different story if he had exhibited violent or maladaptive behaviors at home or towards little kids, but you say that he hasn't. 

My nephew has autism (he's 6 and still non-verbal, can be violent, has a tendency to elope, basically ALL the things) and I've cared for him quite a bit since I'm the only one my sister trusts. So I know firsthand how exhausting it is. I also know that it isn't morally right to just send a kid away when what's better for them is to remain in the home, with their family. You have to weigh a ton of factors to determine when/if the needs of the family outweigh the needs of the individual. Or when it might actually be better for everyone to change the living situation. From what you've said, I don't think you're anywhere close to that with your SS. That doesn't mean I don't sympathize with you; I know that I could not care for my nephew full time, personally. And it really sucks that your BM is such a POS, mainly because her son deserves better. But you have to consider the total picture from your husband's perspective, and he's in an impossible situation if you're planning to force him to choose. 

I have an autistic family member who was also diagnosed with oppositional defiant disorder. He is a joy to be around, but I don't live with him and have never witnessed his outbursts. From what I have heard of them, I would say a hard no to the situation you present. I really feel for these kids, but if they can't regulate their own behavior, that becomes dangerous.

Comparing the living situation of your stepson, as compared to that of my Aspie (Asperger’s) nephew, I’m filled with pity for the youngster. My nephew was raised by loving parents who did their best to socialize and educate him. They pursued every resource available for children ‘on the spectrum’ and encouraged my nephew in his activities and passions (most ‘Aspies’ have specific interests in which they excel).

Your SS was a loser at the starting gate. His mother has rejected him, his father is unwilling to invest the considerable time and energy required to satisfy his son’s needs and you are overwhelmed with the care of a toddler as well as being heavily pregnant (and hormonal!) with your second child. 

It’s not surprising that you have little time to spare for ‘somebody else’s child’, particularly since he is also a difficult and disruptive teen. No doubt, you are also resentful of his birth mother who has, essentially, dumped her problem child on you. 

Part of the lad’s difficulties are likely his awareness that he’s unwelcome in the homes of both his parents; how awful that must feel! Are there any relatives on either his mother or father’s side who might be willing to foster the boy? Is boarding school a consideration? Your husband’s reluctance to have his son ‘go into care’ is understandable; what parent (apart from your SS’s heartless mother) would be prepared to take such drastic action against their own child?! Would you be able to cast off your own, biological daughter if she became troublesome?

This is an awful mess! I can only suggest that you and your DH discuss the issue with a therapist who specializes in the concerns of autistic children. He/she might be able to recommend some services available to folks in your situation.

I'm so sorry, Hon, that you're enduring this stress during a time when you should be happily anticipating your new baby. ((((HUGS))))

Your from GB. So I really don't know how the whold institution or boarding school that specializes in behavioral issues ..works there.  And if you do leave. How is SO going to work and take care of his DS,  And pay CS..  best of luck.  But you must protect you bios 

A kid abandoned by their mother, who is a significant risk to young children, who is unable to adjust to behave acceptably socially and a dad who is marginally invested could thrive in a structured managed environment where he is required to integrate into the community, gets the academic and counseling focus he needs, learn to live with a peer room mate or several, could thrive in an appropriate boarding school environment where his successes were celebrated, his failures would be addressed, and he could learn how to be himself and part of something bigger.

A kid I went to boarding school with was a full meal deal student.  7th grade through JC2.  He was a few years  younger than me.  His parents were troubled and passed very young. His GPs were elderly and unable to raise a pre-teen.  His family sent him to Military School.  Ultimately he thrived, and when he graduated he went on to a Military career. He went the full retirement distance in the Military and is now an internatinal security and safety consultant.  He was a piece of work in his early years at school.  He was scrawny, sickly, awkward.  That formative foundation gave him confidence to make a strong life as an adult.  In hind sight he was likely dealing with any number of then not yet created/identified XYZ LMNOP syndromes.  Structure, support, +' (accentuate the positive), guidance, mentoring, consistency, and accountability can work amazing results in young people who need something different than to raise themselves in an under structured less than demanding environment that they struggle in and ... could do irreparable harm to himself and others.

There are options to get him what he needs, remove him as a risk to your young ones, to you, and your marriage.

Beside dumping the kid on you?  Is he taking off from work or hiring someone, or a group of people to care for his DS.  It's seems like BM did nothing for 13 years. And ie DH also did nothing for his 13 Years .  So now what?  DH must have a answer?  A care plan. A medical plan. Not just take him. HD must make you feel safe 

I can really feel the weight of your situation, especially with a baby on the way and your concerns for your younger child. It’s tough to know how to respond to challenging behaviors, especially when you’re doing all you can to ensure a safe and positive environment for everyone.

As someone familiar with autism spectrum disorders, I can tell you that social boundaries and emotional regulation are especially difficult for many children with autism. Often, these struggles stem less from malice and more from an inability to understand social norms in the way that neurotypical peers do. Many children on the spectrum don’t intuitively pick up on unspoken boundaries or consequences, and they require lots of patient, consistent guidance in learning how to navigate these situations. The fact that he’s acting loving and caring at home suggests that he is likely feeling safe with you all, which is a positive sign that he’s capable of positive relationships and emotions, even if he has trouble in certain social contexts.

It sounds like his school and other agencies are already involved, which is a great start. While I understand your reservations and the fear of potential behaviors at home, it may help to remember that many kids on the spectrum do respond well to the right therapies and strategies, especially with a team approach involving family and school support. This can be a long process, but it’s not hopeless. Perhaps working with these agencies can help you explore therapeutic strategies, social skills training, and boundaries tailored to his needs.

You have every right to feel comfortable and safe in your own home. But maybe there’s a path forward where everyone can feel supported. These behaviors don’t mean he’s a bad kid—just one who’s struggling and needs extra support learning what comes naturally to others. As a stepmom, your role is challenging, and it’s okay to feel conflicted. But stepping back to look at these behaviors through the lens of his autism might bring a bit more understanding to the situation.