I need advice, what should I do?

So I have a female friend that I've known for about a year now and we recently started talking romanticly and are in a relationship. There are two problems. One is that I find that I'm actually not that physically attracted to her and that most of the time that I think of her sexually it's not exciting to me. 2 is that she has a lot of trauma from her childhood thar she is recently confronting and it's causing her to be mentally unstable to the point that I will tell a joke and she cries which makes me feel aweful. I hate this because I love her, she's like my best friend but the combination of not much physical attraction and the feeling of walking on eggshells due to her mental problems make me think maybe I should cut it off now before it goes further. What do you think I should do? And am I in the wrong for staying with her if I'm not sure I want this?
I need advice, what should I do?
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