Sorry, but that can happen.  How you and his child with you is going to be taken care of.  Add that to the mix.

You are going to have a problem with your SO wanting you to be in SD life.  That means going out together as a family. Vacations together.   Where does BM fit into this.  Do they play happy family for this child. As common party's. Going out to dinner together??? 

Forget about everything else, it doesn't even seem that you are in love with this guy. You weren't ready to move in with him but you did, anyway?

You were going to end it, but now, you are pregnant again?

Have you considered counseling for yourself?  It sounds like you have some serious issues to work thru.  And, several lives are dependent on the decisions you make.  I had trouble adjusting to being a stepmother.  In a crisis situation, i went to counseling and it was the best money I ever spent.  Good luck!

I would have a get out plan (that you don’t have to go through with). 

This is not going to be an easy relationship for you unless he is willing to be flexible with his opinions. 

Listening and compromising with each other could make you both compatible., but it seems he wants things mostly on his terms. Can you live like that? 

Potential step children can be hard to bond with, even when they are on best behaviour (what will it be like when this child is older?).

I admittedly took a few months to bond properly with my first child (he was premature so my hormones were messed up). 

My other children I had a ‘sudden rush’ of love for them when they were born so it was a lot easier, although this didn’t help me like my stepkids. In fact I found my step children less tolerable (they were adults, and I expected them to behave like adults). 

Even when you love someone it isn’t easy, I don’t recommend staying if you don’t both love each other. 

This comes gradually I feel. It doesn't happen overnight and absolutely can not be forced. You or the child will start to resent him and one another if he continues to push so hard. You need to think about whether you want a relationship with him or not. Because it sounds like you aren't exactly set on even that. Then if you decide that that is what you want then naturally you would want to start engaging in some sort of interaction with his child. If you guys live together and the child is coming around I don't really get how you can not have any sort of relationship or interaction with her? Do you guys not see each other at all? If you do see each other or are around you'd like to at least show some type of positive interaction to start because you are the adult and you and him will both lead how the energy with this process is. It's definitely not easy. I did not love or initially see my boyfriends child as my own at all at first. We met and that was the only expectation was to meet and interact. We said hi talked a bit sort of like a date but getting to know the child and the child getting to know you. The love comes over time. And it may not come at all really depends on the situation. I've had issues or points where I wanted to disengage because my partners child is older and can sometimes get an attitude or be difficult but I feel like I got to that point after trying to do what I could to make things right and it now working. Things are pretty good at the moment but it's like a roller coaster. Everyone is different. If you want to try then go for it put some effort in but if you don't want to that's ok too but you should consider how that will affect your child and your child's relationship with their father and their sibling because that is now your child's sister. You should also just be honest with him if it's not something you want so that you guys don't waste time or confuse the children.

Offensive manner...

but staying together or choosing to be an exclusive couple (which is what your post insinuates or states from what i have read), is stupid and not feasible long-term. This fantasy of a 2 parent household and is a main reason why you are an exclusive couple is not feasible long term.

a long term couple looks towards a united future together, caring and loving one another, have common interests that attract them to one another and have chemistry.

it appears you have none of these basic foundations. Sex is sex and people who marry for sex, because the other person is good looking don’t end up with successful long-term marriages or relationships. The sex can go away at times when you age, you age so beauty goes, what will hold you together as a couple?? Saying we’re doing it for the kids isn’t good enough because kids will pick up you 2 have nothing in common together interest-wise, they will see you 2 aren’t right for one another and will not feel like they have a stable home...

your family and his family are not physically living with his kid and of course his family will be biased and soew the “love his daughter like your own crap!!”

heck my husbands exwife tried sabotaging each pregnancy or did her best to not get pregnant with any of hubbys kids, when they were born she did the bare minimum on purpose, left them in soiled diapers all day so hubby could change them when getting home from work, cooked plain white rice and a fried egg pretty much everyday because she didn’t want to learn to cook.

she had the nerve to call my sil bragging how i love her kids like my own. Damn woman!!! Your 3 ferals are such useless pos that are not going to succeed in life or launch, they are disrespectful and unpleasant and respect no boundaries of ours. You didn’t even want your kids but you are pressuring me to accept them as my own??

that will never happen for me as there is too much bad blood. The abuse from them, i will never forget or forgive, i just disengaged.

op, you do not mention anything about bio mum, is she high conflict etc?? If she is, you will hate this skid more becausebad behaviours will increase over the years...

Do not get married unless you want to spend THOUSANDS of dollars to get a divorce, one to include the complexities of child custody, visitation, support, etc. If your heart isn't in it...then do what you need to do to take care of yourself