Ex gf pregnant

Ok .. so my ex and I have been off and on and went through hell and back anyways he had a new gf for like 6-7 months and a lot happened now they have been broken up for about a month and him and I just kinda gravitated towards each other because we love each other like crazy .. anyways we were finally doing so good and then his ex called and told him how she’s pregnant and it’s his and honestly my heart feels like it’s been ripped out and lit on fire. He asked me if I’d stick around and I said yes of course like I love this man so much and I know it’s gonna be stressful but she texted him and said she doesn’t think she can do it by herself she also has a kid already 🙃 that he was taking care of and I feel like I’m watching him create a future with someone else and hearing him say I’m gonna be a dad excited but scared hurts because I wanted us to be the ones to experience that together.. I’ve cried for the past 3 days and I told him I’m scared he’s gonna leave me and go back to her because it’s what would be best for the baby and I hate I’m selfish but I just don’t want him to leave me , he says he can only promise me rn and that he’s scared too and I’ve taken into consideration that he’s scared shitless about all of it but he’s not realizing how damaging it is to me.. I don’t wanna leave him either and ugh like I do t normally post on her but I’ve never had to deal with this and I just want someone’s advice on this whole situation :/