Can you give us a little more detail please about what you told him and how he reacted. However, based on what you have said, this is what I think:
Well for one, don't give up hope. I imagine it is disturbing even to open minded people, he hasn't just shunned you. I know you want immediate understanding, but you are unlikely to get that. Be happy that it wasn't nearly as bad as it could have been.
Be ready to talk to him in more detail. Make it clear that this doesn't replace him, and you don't expect him to take part in it if he doesn't want to. However, also make him realise that this is part of you and it won't go away. If he does indeed care for you as much as you care for him, he should be able to get over this and still love you, even if he is uncomfortable about this.
To get understanding of how you feel, you will have to go over what this means for you in detail. How it affects you and what you get out of doing it. He has no chance of understanding how you feel, unless he understands what you feel. Acceptance and understanding will be more difficult, but if you are open about it and he does love you, you will be able to slowly move towards that sort of position. If he can't learn to deal with it, I know you care about him now, but is that really the sort of person you want to be going out with?
Prepare for the worst, hope for the best. Good luck!
--- mzkkbprmt