The feeling you are experiencing is called relief. What you are experiencing relief from is called gender dysphoria. I was in denial for decades, not wanting to believe it was real. I, too, found it terrifying to admit to myself or anyone else that deep down what I really needed was to live as the woman I truly am.
When our outward appearance is at odds with who we are, it creates tension, depression, anger, anxiety, all kinds of stuff. Just dressing like who we actually are gives relief from the side effects of our false life that we have presented to everyone our whole life. Letting go of all of that, even temporarily, feels great and liberating. Because it is.
I would recommend finding a therapist who specializes in gender dysphoria and trans issues. Get to know yourself. Have a safe environment to verbalize all of the stuff you've been hiding. And most of all, accept that gender dysphoria is very real and you're not crazy, or a pervert, or anything else. Once I got to the point where gender dysphoria was life threatening and I knew I had to do something about it or die, I began earnestly researching it and reading other people's accounts of their experiences. I found out I wasn't unique. Many of their stories were strikingly similar to my own. How can that be? Well, it's because we're all experiencing a very real condition with common symptoms and common treatments.