Sorry, I had to go out for a Mother's Day dinner with my family and didn't have time to post earlier.
When reading your opening post, I wondered about something. Has he ever been seen for MH issues? Because what you're describing sounds very much like someone with some degree of depression and anxiety.
He's likely functioning at some level; work, for example? He may be self-medicating with the alcohol for social situations (such as when he was dating you.)
I've struggled my entire life with similar-sounding symptoms. I am somewhat withdrawn. Very low self-esteem, insecure, and constantly worrying what people think of me. Even at home I feel that way. As a teenager, I dated but really "blossomed" when I started drinking just a little. It enabled me to get out of my head and enjoy myself. Dancing, parties, etc. But due to addiction issues in my family, I'm always afraid to drink very often. I quit going out to clubs and my husband said I wasn't "fun" anymore.
With the right medication, I'm no longer so nervous about being out of the house, and have started enjoying life more. I'm not nearly as self-conscious. I feel better overall and aren't sad and worried all the time. I get things done around the house, and am a lot more pleasant to be around. It's not perfect, but I'm functioning and participating in life again.
Seeing someone and getting help has been a lifesaver for me. Literally, I think. More than one person suggested it to me, but I had a negative experience when I went years ago. I finally got so miserable that I gave it another try with someone different. I've been a pretty decent mother (my kids are in their 30's) but if I'd done this when they were small I could have been so much better.
If any of this sounds familiar, I hope you can convince him to see someone and get help. I think it would be good for all of you. Living that way is so painful, but I thought I hid it and never realized how much I was hurting my family.
He may not realize either, even if you're telling him. I'm thankful my husband never gave up on me, but also that he was strong enough to let me know he wasn't going to keep accepting the situation indefinitely. He said "Something has to change. I can't keep living this way." in a calm voice, which let me know he was serious. No threats or ultimatums; I think if he been angry I would have dug in my heels. Instead, he was a little sad and resigned. Just telling me how he felt. And for once, instead of thinking he was just mad and didn't mean it or that it would blow over, I believed him.
Good luck! 💙