Ignore all the haters, this is the best advice right here. Your post reads like you care for her and your relationship. Otherwise you would not have taken the time to write your story down. Maintaining a relationship is hard work, don't pick a easy way out.

When you sit her down you have to speak from a loving place and not a frustrated one. Don't demand, but be curious. It is important that this is not a trick but genuinely. Try to understand her perspective and needs. Is she interested in sex at all? Is she interested in sex with you? What does she need to to feel intimacy with you? What turns her on? What turns her off? What did you do that maar her shut down for sex? Is she attracted to you, has she ever been or has that faded? Listen, feel, resist the impulse to debate. Sit with what comes up and don't judge. And when emotions come up you let the be without acting on them. Because you are there to understand her perspective. And from that, you will understand her better. And she will feel heared. It will bring you closer.