There are definite similarities between our Hs. Some aspects are very familiar.
Like you H's mother, my H's mother was very volatile and pretty nuts. She had good reason to be unstable and neurotic though because she left a concentration camp to work in the UK as a domestic when she was 17 and never saw any of her family again. They were all gassed. My H never knew his father who died when he was 4. His mother was the OW so I'm not sure H's father ever lived with them anyway. His father had a family and a son who didn't want to meet H until a few years ago because he felt loyal to his own mother who had suffered a lot because of the existence of H's mother and H in their father's life.
H was raised by his mother and by a Christian nanny whom he was very fond of. H definitely had a terrible R with his mother. In fact, I'd go so far as to say that he hated her. He had his PA just after his mother died 8 years ago. Weirdly, OW is Jewish and I'm not. He was back to having 2 women in his life: one Jewish and one Christian. Neither I nor OW is religious and neither were his mother and nanny.
Like your H, mine is bright (in a slightly absent-minded professor way) and can be funny. He is also loyal and loves his kids.
Like yours, he has huge issues with self-deprecation and feeling inadequate, and often turning that into an attack on me for disrespecting him. The other day he even went as far as to ask me whether I thought S17 was not focused on his future because he had a father who is a loser as his model. I was appalled that he could think that and say it.
H has definitely under-achieved relative to how bright and talented he is. He was a bit of a musical prodigy as a child. He was also brilliant in chemistry. He wanted to go to med school but got into drugs instead and got kicked out of uni for manufacturing drugs.
Right now (in the last couple of weeks), he seems to have got his drinking under control but he is on 2 meds (Zyban and Duloxetine--I'm sure they are called something else in the US).
Also, like yours, my H is incredibly withdrawn emotionally a lot of the time.
Me: 51 H: 52 T: 23 yrs M: 19 yrs S18, D16, S14 (special needs) PA: 2003/2004 Piecing: 2004 on Suspect H had EA: 8/2012-12/2012