You should definitely tell him!! You never know he could be excited about the baby and if he's not you guys can talk about it and make a decision together.
U should tell him, u won't know his response till u tell me so don't assume & honestly if u hate yourself for getting an aboration why would u even consider doing it again?? Regardless of the situation your in, u have a human life inside of u and it was your desicion to even let the life happen, talk to your bf about it. He could be happy for all u know. Good luck with whatever u decide.!
You should tell him! Regardless of the outcome that baby, no matter how young, is still half his. He will be more upset if one day down the road he finds out you did that without discussing it with him first. The most important thing in a relationship is honesty and if you can't get past this, it's would've lasted anyway. Remember this is not YOUR fault, both of you are responsible and you shouldn't have to handle it or make these decisions alone.