Reading your post sounds like a page out of my life.
My husband of 10 years is bipolar and is on medication, but not under the care of a psychiatrist or therapist at the moment (med dr is prescribing the pills).
When we first married, he had not yet been diagnosed and I immediately noticed that something wasn't right and all the arguing, betrayal, and lies began. Well, after about 6 months, he just up and left. No notice or anything.
We worked through that episode and he sought psychiatric help. Diagnosis was made and he was put on meds. The episodes have never stopped. We have been through tons of therapists and doctors.
Twice I have come home to an empty house where he has left me and not even said a word. Like you, I had no clue he was planning on leaving. That is extremely painful and I'm so sorry you had to experience that.
He has filed for divorce 3 times. He has gone from being very successful career wise to working an entry level position. His behavior is simply unbearable at times plus it's been physically dangerous to me.
We are now in the process of another cycle (right before spring has been a pattern) and we are splitting up once again. Unfortunately for him, this time it's for good. This came right after a pleasant vacation. The very next day actually. We had plans of moving. Big plans! I heard I love you that morning, then I hate you that night. If I could tell all the details your head would spin!
Although, I wanted to stick by him, I think I have had more than enough. I simply can't do it anymore. It is not healthy and it's taking it's toll.
Not everyone is affected in the same manner and not every situation is the same. I hope you can get your husband the help he needs. I would just hate for anyone to have to live their lives the way I have for the past 10 years. I always had hope, but now I feel like a fool. Take care of YOU first.