It's been a while and he has been concealing this... We had a really bad time after my misdiagnosis, I believe it was a severe trauma to him to see his wife insane and on heavy medication. It was over a year ago, I went to a different doc who got me out of this sh*t.
But my husband remained traumatized. He developed bulimia, he counted every calorie, then exercised with no moderation, then ate whatever he could grab, then vomited...
I thought he got better lastly but only today I learned he threw up every single evening for the last week. I don't know what about the weeks before.
I'm devastated. I'm trying to convince him to go to a therapy but he is resistant, he doesn't want to talk about it.
I love him. I want him to be happy and healthy.
I have no idea what to do

Go to therapy with him. I was in a similar situation with my wife's health where she needed more care and I didn't have time to eat. Also I felt more responsible for her health than mine. You need to let him know that the pressure is gone and he can relax and feel better about himself. Be supportive while still taking care of yourself.