AIO To my fiancé after he texted this to me?

Me and my fiancé have been together for 6 years, and this weekend, things blew up. We were quite drunk and a little high, but he told me he was trans. We had a long conversation about it, and he told me he'd start presenting as a girl.

Flash forward a couple of hours later, he sends me this. By the end of this text thread, I started to have a panic attack because he wasn't the person I agreed to marry anymore.

After a long conversation with him, I've realized he doesn't even know what being trans means and literally didn't even know what he was saying. I'm still freaking out to be honest. Am I overreacting?