Pregnancy hormones break up...

If you break up with a guy when you were pregnant and hormonal, would you expect him to be patient with you or is it okay for him to just run off with the first female that comes along? I feel like I was pressed to the edge when I was pregnant and the fact that we ttc on purpose, that my ex shouldn’t have just given up and walked away. Now I’m forced into a coparenting relationship with him, sharing my children, while according to him he’s found the love of his life.