I can relate, I was raised where negative emotions were not okay, I had to pretend to be happy and compliant no matter how I felt. My mother would shame me if I expressed emotions in convenient for her. So I grew up to doormat in personal relationships and at work. What helped me significantly at least expressing myself was taking assertiveness training from a company that does business management class learning tools on how to deal with common work situations that use to completely overwhelm me. I learned how to stand up for myself without being an emotional wreck. It's so much better than being a human doormat and then exploding in anger when the unspoken resentment and hostility got too much.

I know this might sound like a strange suggestion but what about taking acting classes so you can learn to connect your feelings to physical expressions?? This might sound weird but sometimes I think when we were really shut down as kids we didn't learn things the way kids learn them- physically. I know at least I internalized and intellectualized a lot of what was going on when I was young and that's not how kids learn. Kids learn by doing. Maybe some lessons in how to emote properly could help???