Having unprotected sex is ALWAYS going to give you a chance of getting pregnant. For ten months straight I had unprotected sex with my boyfriend and didn't get pregnant, but now I have a six month old. It is possible that you aren't, but it seems very likely that you could be pregnant.
Your boyfriend needs to realize that if he wants to have sex with you, then he needs to be prepared that you may in fact get pregnant. This isn't just you. It was a 50/50 choice that both of you made which led to this. So you BOTH should stand up and take responsibility.
If your boyfriend chooses not to be involved, then LET HIM LEAVE. He doesn't love you, anyways. If he does then he'll support you no matter what! It may just take him some time to come around to the idea of being a daddy and he'll just realize it on his own eventually. But if he doesn't... then be strong and take control of the situation!
This may be his baby... but it is also YOUR body. He isn't the one who will have to live with the decision of an abortion, it's you. He does have a right to know, so you do need to talk to him about what's going on but make sure you're going to be strong enough against an abortion. Remember, adoption is always an option, and a much better one than an abortion.
Abortion is very un-healthy for most women. You should learn what you are going to do to your body during the process. Go research it! I do know that from girls on this site like GangY, abortion is a very painful, regretful experience that no one should have to go through.
Wait until you've missed your period and you can try a home test just to check, but a doctor's test is always the most reliable. Whatever the result, I hope you really learn from this and be safer next time. Good luck!