I just keep sobbing uncontrollably. I still love him so fuxking much and I want the future I've built back, I want my life back. I fiercely don't want to be with anyone else, but my head tells me I can't trust him.
I don't want to build a new life, I don't want to be a single parent with a baby not even 5 months old, I don't want to date or meet new people. I don't want to. I was so bloody happy. I don't understand
You are going to go through a period of grieving for the life you thought you had and the future you thought you would have, together.
You are understandably floored right now, but you will gradually begin to piece yourself back together. You will eventually feel a huge amount of anger toward him for what he took from you, for the way he failed to value what he had, and for casually throwing away not only his own home life but yours, and most of all for what he did to the family your baby had.
You don't have to think of someone else at all, not ever, perhaps. Leave all that to fate. There is nothing to be gained from thinking about any of that now. But don't despair. If the right man is out there for you, it will happen. Leave it for now.
For now, concentrate on leaning on other people, eating whatever you can, sticking to a healthy routine of eating, drinking water, getting a little exercise and fresh air, and taking each day as it comes.
You are so brave to have done the cancellations and spoken to people. Make sure you take the time to give yourself a huge pat on the back for your courage and smartness.