No, it is not.
My friend was in a situation just like that.
She was fifteen and he was eighteen, they went out since she was like ten and grew up together, they fell in love.
But he got her pregnant and when he found out he started telling her to get an abortion and hitting her and abusing her and whatnot.
Everytime someone told her to leave him she'd be like 'i love him more than anything, i'm pregnant with his baby.' and all this other stuff.
If i were you, I'd try to talk to him about it and try to get him to change. Try visiting him and talking to him..try getting him to understand how you feel about it. That sounds like an unfortunate situation, I'm sorry to hear about it. I hope it all works out for you.