I feel for you Clothkits. My husband has a bipolar diagnosis and is on mood suppressant medication. He was not diagnosed until we had been married some years but I did always think he was a Jekyll and Hyde personality.
Fortunately for me he does not have low episodes. We have recognised that stress is a trigger for him, he becomes high which can manifest with distraction, poor sleep, constant talking, manic episodes. It’s very difficult to explain but when he is like it he has no empathy of my feelings, everything evolves around him. He has been hospitalised (MH hospital) once in the 24 years we have been married, usually we manage between us and it fades over time and I get my husband back. When he is “in it” I feel lost and alone but he does come out of it and I get him back.
There are support groups out there for loved ones, I was given information by his MH team, I have not used personally as I have so far managed with the help of very supportive family and friends.
Sorry not really any advice but you are not alone. I do hope you can find some support.