I of course don't know your bf. But I will tell you about other Muslim men I have known (and men from other cultures as well) who have dated western women. This may or may not apply to your situation, but at the very least is might be worth thinking about.
As others have said, your bf is breaking Muslim law simply by dating an unbeliever. Why would a Muslim man do that?
Well, he might be a "liberal" Muslim who is rebelling against tradition, but if so I would think that he WOULD have introduced you to his parents by now. If he is hiding this relationship from them, then he is probably NOT filled with strong convictions about dating you. So I would reject this explanation.
He might be hoping to convert you to Islam. Since that is not an option for you, I would break off the relationship.
Or....he might be like too many men I have known who come from cultures in which male/female behavior is very regulated. The men I am thinking about have had the attitude, "Hey, western women are so sexually free! I will have fun with them before I settle down and enter into a traditional marriage according to my people's traditions." I have seen this not just with Muslims, but with men who were raised in traditional Japanese society too. (Of course, there are plenty of devout nonhypocritical Muslim men too, but they are probably not going to be sneaking around hiding a taboo relationship from their parents!)
Again, I cannot presume that this is what your bf is up to. If he is just using you in this way, that has got to be a very painful thing for you to deal with. I hope it is not the case that he is like this, but as I suggested earlier...it is worth thinking about, even if to convince yourself it is not true.
How do you know his parents hate you? If you have never met them and this is based purely on what he has told you, that could mean that they do not even know about you and he is playing games with you by telling you this. On the other hand, if you have met them and you have felt that animosity yourself, that counts in his favor as far as truthfulness goes.
I wish you the best.