Hi and thanks for coming to us with your question.
I will do my best to assist you with your problem. So if I understand correctly, you have a female friend with whom you had some sexual chemistry, which eventually led to a sexual encounter between you. After this, however, she said that she wanted only to be friends and now you are best friends. As you grew closer, she confided in you that she used to have a girlfriend. You still want to be her friend but you are at the same time, hurt and perhaps, bitter over the fact that she doesn't want to be more than friends.
Well, first off, what you are describing is probably one of the most common scenarios that exists when it comes to friendship and dating. One friend has strong
romantic feelings for another friend but the other doesn't feel the same way. I know it may feel like the end of the world now but this will blow over. There are plenty of fish in the sea, unfortunately, this will more than likely happen to you again. You may even end up being on the other side of things at some point, and that can suck in a whole different way.
The last thing you want to do in this situation is allow your emotions to get the
better of you and come off as a jerk. Making lesbian jokes is extremely oppressive to your friend and if she was to mention you making these jokes to someone, that person might get the impression that you are an intolerant bigot. Think about it, your next crush might be one of her friends so keep it classy!
Try to remember that your friend can't help how she feels and she's not to blame
for you being hurt. If you find that you simply cannot prevent yourself from making
inappropriate comments to her, you would be much better off avoiding spending
time with her.
Also, remember that she didn’t want to take it further with you because she worried about ruining your friendship. This shows that she cares about you and values what you already have. Maybe this has nothing to do with her being a lesbian, but rather that she plain and simple prefers to keep you as a friend rather than something more.
I hope this helps, feel free to get back to us with any other concerns you may have.
Philip B. for Alterheros