I have two anecdotes that may help.

One, me. Cis lesbian, or that's how I used to identify. Now I just call myself queer as it's more inclusive. I think of gender differently now. I'm still mostly attracted to women but it doesn't bother me if they're cis or trans, and yes I would date a man (cis or trans) if I liked him. That is not to say that you are obliged to change your sexuality, but it can definitely happen. For me it was learning more about the gender spectrum and really thinking a lot about what gender and attraction meant for me. I'm much less rigid about it now. If there's a connection, there is.

Second anecdote. I have a friend who is a trans woman. She married before she was out, and her wife was 100% sure she was straight and told my friend that if she transitioned, that meant the end of their marriage. But they love each other, and have worked on it. My friend has been out for about two years now I think, and her wife no longer wants to leave. They really seem to be making it work.

I do understand where you're coming from though in terms of your identity. I used to be super invested in my identity as a lesbian and to be honest, when I had my first relationship with a man since coming out, it messed with me a lot because I didn't know what it meant for me in terms of identity. Your feelings are completely legitimate either way. There is no shame in staying with your partner and no shame in leaving because it doesn't work for you. Really whatever works for the both of you is the right way. There is no one answer.