I'm sure that she loves, and does, in fact, have a deep affection for you. But you've had the realization that you are a lesbian, and I think in your situation you might have felt that she will be the only one that you will ever feel that way about. Because she was the first. But there will always be someone out there that is not in a relationship that can love you back and not have obligation to another man or woman. They will actually be able to love you back just as much.
After you have a talk with her, and tell her how you feel, maybe you should go looking for companionship with other women. I'm not saying you're restricted to one gender forever. But I don't think you should ever force yourself to be something you're not. And that means if you're just lgbt, then you shouldn't force yourself to be anything else. So if you never feel romantic affection towards a man like you do a woman, then that is where you should find love.
You shouldn't neglect your duties to your faith just because you're lgbt and because some assholes say or think you're "immoral". I can't really speak for other faiths, so I can only speak for mine. And in Orthodox Judaism, it says not to be promiscuous. Both men and women are forbidden from being promiscuous. So hetero
inherently right or correct just because it is between a man and a woman. All sexuality is forbidden besides what is in marriage. And for Orthodox Jews we have the laws of marital separation so even that is restricted. So if you ever have some guy or girl come down on you for being lgbt, and he\she fools around outside of marriage, they're being a huge hypocrite. But that is a Jewish belief, I'm not sure about Islam and if they're allowed sexual relations outside of marriage.
Regardless of what other people think, don't stop with your faith, and don't stop believing.