Hopefully you have friends. You should talk to them. That's kind of what they are there for. If you find yourself really depressed over the situation, talking to a professional is also not a bad idea. That helps speed up the whole "time" thing.
But remember that everything you're feeling is totally normal. Relationships, even if they ended years ago, have a way of sticking with you and shaping you so it's only natural if you feel weird, sad, or even skeeved out. You won't feel that way forever.
What's the best way for a couple to get out of a sexual rut?
People in relationships will be the first to tell you that after a while, sex becomes routine. And those couples who insist their sex is always fiery, passionate, and pornographic are definitely lying. The difference between couples and friends is sex. It's pretty important. That said, when you're with the same person day in, day out, it can, and will, get old. But fear not! Just because you might not be feeling the old repertoire doesn't mean you can't strike up a new one.