That's exactly what I thought when I head-butted up against your wall of text & story of SM to 5 kids. (Take the cap-lock off, makes reading easier)

If you were a friend, I'd tell you to gather your stuff & high-tail it out. Run.  

You will most likely be responsible for 5 kids for the next 20+years. They can all move in any day & your SO will be left holding the bag.  Can you imagine the fridge & pantry necessary for a 7 person household ? Dentist visits, electric bills --- I feel badly for you. 
 

Circling back to some of what you wrote --- Casino? Really? As someone else memorialized on this board --- you must be "dickmatized." Sorry for being vulgar but I don't have any other understanding as to why you are still with this man who has so little going for him by your post.

If you're frustrated now, I promise you that daily life will get worse as your SO fails to parent these kids. (Be wise re: birth control) Life will not magically get better & having CPS in your life is no fun. Trust me on that one.

Anyway, good luck --- no, you do not need to care more for these kids than their bio parents. Childcare, food, a roof over their head is the parent's job, not yours. 

You sound like a decent person & I'm sorry that you're in this position 

You should not babysit.  If you don't want to babysit, do not let him pressure you into doing it. BUT - I would guess that if you don't babysit, you will find yourself out of this relationship, because your boyfriend will need a girlfriend who is willing to provide free babysitting services. And that's OK, because you can do better than a guy who would just abandon his kids for months with an unsuspecting relative who agreed to babysit. What decent person does that? 

You're being used. Your boyfriend is not a decent person. Do yourself a favor and refuse to watch his kids. It's not your job. With any luck, that refusal will be your ticket out of this no-win (for you) situation. It's only going to get worse. And whatever you do, don't get pregnant!

Let's see...

• You're with a guy who has five bios and two steps, you are child-free and don't like kids.
• He has 2 bms one of whom is in jail but will be getting out soon.
• You moved in a month after his second bm went to prison.
• He wants you to be his unpaid babysitter to his two feral sons while he goes out and has fun without you (slave, much?). So he doesn't parent either.
• He guilts you for not taking on his responsibilities towards his kids.
• Nobody else will babysit because he doesn't go back to collect them.

First off, you are not a stepmother. You are his girlfriend. Even if you were a stepmother, his kids are his responsibility, not yours so, no, you should not feel bad about not wanting to babysit them. Especially as he clearly makes no effort to parent them, to raise them correctly - he just palms them off on other people. Him telling you that it is your duty is a load of rubbish. All I can say is that if his sons are destroying the house while so young, imagine what things will be like when they're teens and bigger and stronger than you.

You're clearly unhappy there, you need your space, you are a clean and neat person, you don't even like kids, so don't feel bad about wanting to move out. That's what any sane person would do. 

Why did you move in so fast? My guess is that he was love-bombing you, right? Promised you anything and everything to get you into his place so you could keep his house clean, take care of his kids and so on. My guess is also that, once you were there, things changed and you were no longer treated like a princess. 

You said the kids weren't in school - is that because of distance learning or because he doesn't see the point? 

What's going to happen when BM2 gets out of prison (what is she in for, by the way?).

Please, please, please raise your standards and leave this worthless bully (yes, he is). You deserve way better than to live in this chaos and drudgery. Whether you should babysit his kids or not is the least of your worries. Pack your bags and leave today. This is no way to live.

((((HUGS))))

Run far and fast. Find a responsible man who wants a partner, not a live-in nanny so he can go gamble his money away rather providing for his too-many kids. 

You are being used!!! Get out of this situation and don't let this man gaslight you into questioning your own common sense.

Don't know what to do?

Move out. He "moved you in", like a live in nanny. Quit.

LOL, this has to be a joke guys. It's the stereotypical young girl becomes a nanny nightmare for the older guy with multiple baby momma's....Is school out this week?  I call CREW>  Check the profile too

Either bored kids do this or it's a repeat offender with some variation of the same story.  Don't waste your time.  If they are stupid enough to get involved in this situation they deserve every bit of used up they get.  

WTH are you doing with this guy? 5 kids and expects you to take care of them...no way! You are only 6 months in and you have no children. Think how it's going to be a year or 2 from now...get out of there ASAP. Really, it's going to take a lot out of you and you will lose yourself in the process.