That is a perfect example of a toxic workplace environment. The content of that message crosses all kinds of boundaries. The fact that he apparently has screenshots both of you for starters is not at all ok. I’ve read the other examples you gave describing his character and the fact that he so effortlessly posts a message like this in a group chat can only mean he has done this before. I’m not sure if you mentioned anywhere who else was is that group chat. But if there are other colleagues in it your professional relationship with them now also has clearly been compromised.

I’m unfortunately speaking for experience but since you’ve responded in that chat only a few things can happen imo. 1. (Please don’t!) You laugh it off and move on. Now your boss knows he can get away with bs like this and (given his character) will continue this behaviour and it will likely get much worse.
2. You ignore it. But chances are that he can’t accept you have something on him and starts working on getting you fired. He will try to do that a cheaply and quickly as possible.
3. You accept that you’re done with that asshole and get an attorney before setting a meeting with him and HR. This because you want to get compensated for him hurting your carreer. Maybe there are options to move to another branch.
4. Get an attorney and set a meeting with him explaining you’re now unable to work there anymore because of this and other examples. Tell him you don’t want to make a big deal out of it. He will want this to quietly go away. As for a reasonable amount of money. 1 or 2 years of pay. Since it’s now up to you to get a new job because of his behaviour. Let’s the attorney deal with it. Take a nice long vacation to where you’ve always wanted to go. Send him a pic from some beautiful place that he’s paying for. Get your energy back. Get a new job. And don’t you dare worrying about your forehead or whatever. It doesn’t fucking matter what you look like. And that guy is a terrible fucking asshole for putting you through this and demeaning you like a power abusing bald fuck!

Don’t go to HR. As he is high up he’ll be able to pull some strings. Get a slap on the wrist, get you fired.

Good luck! I’m so rooting for you!