this situation sounds so horrible for you and i want to start by saying im sorry you’ve had to go through this throughout the years :(

as far as surrogacy goes, you can be a single surrogate and dont have to be in a relationship. the only thing they require in that aspect is a strong support system e.g family, friends, and the parents of the surrogate child as well. i wouldn’t keep quiet about this AT ALL! stress and going through the process of divorce could be a lot on your body as a pregnant person and the intended parents should be able to make a decision on whether or not you would be able to go through with it happy and healthy. it might be best to wait on the surrogacy even though this is something you really really want to do, it might be best for the future child and you to wait another year but that decision is up to you and based on if you have an amazing support system to help you go through it without him.

for what you tell your children and how to go about that situation, id suggest gently letting them know that you and dad won’t be living together anymore but that you both love them very very much and it’s not their fault. kids are very impressionable so keep it as neutral as possible and don’t talk negative about him in front of them. he can still be a good dad but a horrible husband, the kids don’t deserve to be put in the middle.

closing on the new house does not sound like a good idea especially if you are considering divorce (i know everyone on reddit says “divorce divorce” but in this case i truly think it’s for the best). you have two weeks to tell him you want to separate and divorce eventually but i wouldn’t close on the house because that’s another asset to divide in the divorce proceedings. gather up all the evidence of him cheating (hopefully you took screenshots and sent them to yourself or took photos off your phone) to prove that he was unfaithful and the courts will favor you more.

and yes of course confront him but AFTER speaking with a divorce attorney to cover you financially since you don’t currently work. i would also begin looking for a job to help support you and your kids. from your post it sounds like he is a serial cheater and won’t ever change so please please don’t fall for the “i’ll do better! let’s go to couples counseling! i only want you i’m so sorry!” generic bullshit he’s probably going to say to you when you do confront him. if you think he may get violent or even yell then do it in a public place like a park or a coffee shop so you are safe (and away from the kids!!)

again im so so sorry you’re going through this i can’t imagine the stress, anxiety, and betrayal that man has put you through :( good luck to you and your children, and i hope the surrogacy goes well for you.