Couple of points, Tink:
1. Your husband is a crossdresser (noun). He was before he met you, he would be if he had never met you, he will be if you stay, he will be if you leave. It has nothing to do with you, so when you talk about it like it's some sort of competition between you and some imaginary woman, you really, truly, shockingly don't know what you're talking about.
2. But let's say your ridiculous scenario is real, and this is you vs. imaginary woman; I hate to break the bad news, but technically, YOU are the mistress, not her. She was there long, long before you. She knows things about him you'll never know. She's ALWAYS nice to him. She always treats him respectfully, etc. Are you sure you wanna go up against this girl? (Hint - stop fighting her and make friends with her. Life will improve dramatically.)
3. The part of your quote I put in bold is perhaps the most cruel and vicious insult I've ever read on here. If you really feel that way about your supposed partner in life, well ... that's your business. But, yeah, that comes off absolutely hateful and I was disappointed reading it.