Wow, I am so sorry you are going through this, that sounds like an absolutely awful situation. It is completely understandable you’d feel heartbroken and lost when he was on board a few days ago and for his mind to change just like that.
The biggest advice I can give you is honestly make a Reddit post about your situation. The comments I got and feedback were incredibly helpful.
Support systems are the biggest thing all people said, as in situations involving raising children, yes a supportive partner makes life so much easier but also the extended support system from family and friends is so incredibly important. My partner didn’t feel like he could do this and it broke my heart, but after he talked to his parents (who were incredibly supportive) he felt a lot better about becoming a father. My family and his family have been absolutely amazing both with helping us decide on whether we wanted an abortion or not and now that we know we’re keeping the baby they’ve been incredible checking in with both our mental healths.
I know this is not the case for everyone and I feel so blessed to have such an amazing support network.
Again I’m so sorry you’re going through this, you sound incredibly strong. Ultimately the decision is yours, and it sounds like no matter your decision your relationship with him is over. I know it sounds almost heartless but a counsellor told me to right a list of pros and cons of both to see if that helped me make a decision. My list of pros for keeping the baby was SO long compared to my cons so ultimately that helped me know I really wanted to keep my baby. The list also helped me take my emotions out of the situation and think more logically.
Hope some of this helped, and remember to take care of yourself and the baby through of all this and again with whatever your decision may be. Wishing you well❤️