(((Selkie)))
Thank you for starting this thread because there is so much of me in it. The introversion, self-doubt, childhood neglect of feelings, all of it. I wasn't put in danger by default of neglect, but I very much carry around the feeling that no one cares enough to protect me, to advocate for me. Midlife hormones have helped with the advocacy!

Teh advice above is really terrific. Just wanted to add that perhaps it would help just to clarify things with your T like you have here. Eg, "you know, I brought up my friendships the other day not because of any problems with
them, but that I wonder if it is normal to need some time to myself........." or what have you. This might feel like you are correcting your T, but you are just steering the conversation back where you want it and explaining why.
This steering of the conversation will also probably feel quite unnatural because you probably have not had the chance or felt empowered to do so before. At least this is very true of me. I never correct people during conversations. Gosh wonder why? Oh the fallout of growing up with Ns...
As for the actual introversion part, I still struggle with accepting it. I still wonder if I'm really an introvert (I am) or if this is because I grew up isolated by my family and their restrictions. It helps me sometimes to know that valuable work is done by people who work alone, although this is never recognized in our society. (what is except for celebrity status??? I digress.) There is a pretty neat book called A Party of One which is sort of a battle cry for loners. But I still wonder why I cannot thrive in the same situations that, what? 90% of other people? do. I thought going to football games was stupid esp. if you were not interested in the game, but everyone went. I cannot stand the herd mentality and wonder if I am just simply a contrarian. If you all say "black", I'm going to stick up for white. And gray too.
I agree that feelings can be so overwhelming that they are scary and make us feel messed up. And that it is true that these feelings were created years ago and we can only now begin to deal with them. If you are feeling overwhelmed there is probably a deeper truth to it, a pain deeper than you could know before.
I previously wrote about an out of the blue experience with an acquaintance saying something inappropriate to me. There was no malice or anything. In fact it was almost like a bolt from the sky, the messenger didn't matter. I totally over-reacted to what was said (fortunately I kept my thoughts to myself). So I sat with my overreaction for a while and wondered about it. I mean, it was powerful, I was shaking, sweating, tingling. It was a physical reaction to the realization that the hostility towards women in my family was palpable in my house growing up and I had to steel myself against it every day. I told my H about it and he told me later that his thought was that things were worse than what I had described. That women were totally second class citizens in my family.
The reason I share this story is because I might have felt "messed up" (and I did) but it was also a sign of healing, that barriers had been cleared away and I could look the monster in the eye. And then I could tell it, "Uh, so that's what you look like...see ya!" and run like h*ll until I could face it again.

Because the monster will still be there when I can stand to take another look.
Hang in there Selkie! Hugs, MP