How am I supposed to do this ????

I have a really shitty boyfriend who only thinks of himself . He proved it to me several times when all I do is give the relationship my all and try to help him as best as I can. 
How can I stop myself from caring or showing him that I care , how do I stop myself from calling him , how do I stop myself from answering his phone calls. 
I'm not happy anymore . I'm 5 months pregnant and he doesn't care how he treats me he hasn't even made an effort to come up with a name for our son or get anything I need for him.
I could really use your gals advice 
Thanks in advance ❤️❤️❤️❤️