Your partner crossed a line when he had a conversation with his ex and they decided you needed to do more. That is a hill I would die on. You have one child, your partner has three. You don't need to make time for or do things for his two kids unless you want to. You need to have a serious conversation with him about who is his current wife and who he wants to make happy - because if it is not you, then you have a tough decision to make.

I am so angry for you. None of this is ok. 

It sounds like there are three people in your marriage, not two. The ramping up of communication, activities, and scheduling since you became pregnant sounds like jealousy and a set-up to me. That your husband is showing more loyalty to his ex-wife than to you is a big problem. That they would dare discuss what they think you should be doing is a betrayal. 
I think your husband needs a wake up call. 
Im sorry you're going through this, especially at a time when you all should both be enjoying your baby girl. Do you think talking with a therapist would help? 

Hon, I'm typing this gently so please read it that way: why should you pay for him to decide which partner he wants? he needs to know what he wants? he can pay for it because the fact that he doesn't know is the answer you needed. Please start putting yourself and your child first, he's not doing that for either of you. 

Oh man... This man has no boundaries or any clue as to how a normal relationship should work. Sure the ex is being ridiculous as they often are but he doesn't have to agree and go along with whatever she wants just because. Your partner sounds horribly insensitive to the situation and your feelings and to me that is the worst part of it all. And the disregard and unfair, unequal treatment of your bio. Do you feel like your life would improve if you leave him and go for full custody of your child considering he has so much energy and time to have with the other kids and bio mom? 

I seriously hope this whole post is rage bait. He and his ex are "we", and discuss OP's performance as a stepmom and jointly make recommendations? The guy says he didn't really want another kid so OP is responsible for everything? But she needs to do more for BM1's kids? And this loser is unemployed. He's like a wishy-washy wannabe Nick Cannon but broke, going back and forth between 2 BMs, just loosey-goosey with the boundaries. He wants his college student BM2 with an infant to pay for therapy so he can figure out which of his BMs he wants.

Fk all that, OP. No mercy with this a-hole. 

Or your home, or your time.  The stepkids have two parents, you are not one of them.  But it's your job to make sure DD gets everything SK are getting.  More in the future ..  that you get alone family time with just you, DH, DD.  just like SK got when they were young.  You are not one happy family. It's your family against SK family. Shocking but true . If you buy SK a great $ gift dies that Thai money away from DD?   
'You should be able to do thing as alone family as trips to Disney..ect. Not having SK screwing them up.   SK understands DD lives with DH 24/7/365.   She gets a lot more of DH then his kids.  That's life

it was DH decision to divorce, His ex. He know in doing so, he would lost time with his kids. He would screw up there lives.  Then DH gets into a new relationship, has another kid. Just how does he think this is going to work?  The world didn't do anything in his first marriage.. But now you are to change it ?  
'DH should just be happy with you and his DD. and create a life he can with you.  Not chase a failed relationship again and again getting no where.  

So he is currently unemployed and has addiction issues on top of still harboring feelings for his ex-wife. You have made the right decision to move out. I would suggest that you follow your instincts and do not let him take your child on his own - it doesn't sound like he could care for her. I know you are overwhelmed right now, but the first thing you need to do is contact a lawyer. I know the laws are different in the UK - but you need to get some sort of order giving you full custody for the immediate future.

Hang in there, it sounds like you are making some necessary changes for yourself right now. If he wants to make the changes to make things right, he can do it if he chooses to. In the meantime, you need to look out for yourself and your daughter.

Just wanted to send you some good vibes, Dam94. I left my addict, abusive ExH when my son was only 18 months old. It was really scary, like jumping into an abyss and hoping my baby and I would have a soft landing somewhere. I did have a little help from family, but I managed mostly on my own. It was NOT easy, I'm not going to lie, but there was absolutely no question in my mind that I would rather raise my child on my own than in a toxic environment. I finished a grad degree and got a decent job, and in retrospect, leaving my ex was the start of a pretty good life. I didn't have the additional drama of a BM or SK. That would have been so explosive.

You have a lot of good feedback and advice here. It makes me realize how sound they are and how I should really take them more to heart when I'm on the receiving end. When the same posters give me feedback, I sometimes filter them through my rose colored glasses, and go into denial a little bit. But I see here that they are right on. Your BF seems manipulative and the "egg" should encompass you and dh, not dh and BM.

Your mate and his X do not get to decide whether or not you do more for their spawn. They are the parents of those failed family breeding results.

Re-read your post from the position of someone asked for advice. You know this is a shit show of monumental proportions that will never get better. End this relationship, nail daddy for a crap ton of CS, and get on with minimizing the influence of this whole toxic cesspool of idiocy on your own child.

Your idiot mate and his idiot XW expected you to infect their kids with COVID while you were positive.  This says far more about both of those dumbasses than anyone should care to know.

Protect yourself, protect your baby.  

Good luck.

Certainly thing must be established .  The ex is the ex.  There is no talking to the ex. Everything is un deleted text.  Save for back reference.  A CO is established.  So everyone knows what dates times kids are with you and not.  How holidays Birthdays ect are handle.  These don't get change.   Any changes go through you to approve. Not SO and Ex playing games .  
This sounds cold.  Like adults can handle it.  But this is why you get into trouble..  SO and the one they use to sleep with haveung old memories are making plans with out you. Or taking over control of your home. Disrespecting you.  Of course you are angry. You should be.  Tine to straighten out  SO.  If he doesn't want another failed marrage he needs to tow the line

Your partner seems horrible.  He didn't want to have kids with you.. he has no empathy for you.. he shares your life with his EX.. I say take the child "he doesn't want" and make your own life without him (except for the support you get him ordered to pay).

Please leave this pathetic apology for aman a d take your life back. Your daughter will be so much happier growing up in a home wher she is loved and cared for.

Your post updates just have me so mad on behalf of you!! Bio mom... Yes she's acting like a piece of crap.. Your husband is falling for it. YOU are the wife/partner. YOU. My husband once said he wanted bio moms rules at our house because that's what the kids knew... And I said heck no... Think about this... We are the woman and adult of our own home and should not have to live the life of another woman... Another woman in charge of our own life. No thanks... Not the life for me. As it is now... This woman is running your entire life. Your partner allows this. You need to be firm with your husband. Tell him his ex wife isn't going to run your house and family and that he better start thinking about the needs and feelings of his own wife unless he wants another ex wife.... 

On top of all of that I just want to validate... That when you were pregnant and experiencing issues and shortly after you gave birth... You were right when you wanted time to yourself.. A peaceful moment with your baby... To bond... To heal.. Don't ever let them make you feel like you were wrong for wanting that or bad about it...you deserve happiness and to be treated respectfully! Please know that ♥️

To have unvaxxed kids thrown upon you while you were dealing with all of that is beyond insensitive... I would have been livid. You deserve so much better treatment. 

Im so sorry you are going through all this. Take some time to read around on here. It sounds like you are being manipulated. You are expected to be providing, and giving, a nurse, a maid, a bed warmer, a chauffeur, etc...all while being a single mom and student.

You dont sound silly at all you sound overwhelmed.

The confusion is probably exhaustion.

What do your parents think of this sorry excuse for a man? What is their take on things?

Im glad you GTFO'ed out of there and away from him.

Get thee to a lawyer, forget the therapist (for now), and get a court order for full custody and supervised visits.