Andrea, I so understand what you are feeling and you must try not to feel guilty. A lot easier said than done I know as I'm in a similar situation, although not perhaps as severe as yours. My husband is totally dependent on me for virtually everything in his life, but he is still managing to keep pretty upbeat day to day. In-spite of his severe disability (acute emphysema, on oxygen 24x7, unable to do virtually anything as just even getting up from the chair leaves him literally fighting for breath), somehow he is able to maintain his sense of humour and I know he does appreciate everything I have to do for him. But, like you, it's not how we want things to be. I'm 78 yrs old now and (touch wood) in reasonable health and want to do so many things whilst I still can. It all seems so unfair, even more so for you with your husband's mental state and a disabled son dependent on you too. But I also know what it's like to fall out of love with a husband. I was married for 30 years to my first husband. He wasn't a nice man but I just put up with him all those years then decided, on my 50th birthday, to walk away from the marriage. But that's another story!
So, back to my current husband (we've been together 27/28 years) and I realized a few years back that his condition was going to deteriorate quite dramatically, but I was determined not to let it totally overcome me too. In a way I suppose I have educated him to accept that I have my life to live too. I have arranged everything in the home so that I can (and do!) leave him by himself for a few hours so I can get out. He wears an emergency alarm on his wrist, we have a key safe fitted so emergency services could enter the house if necessary, and I leave him sitting in front of the TV surrounded by flasks of tea, bottled water, any necessary medications, sandwiches etc. I know others wouldn't dream of leaving someone even less disabled by themselves, but I refuse to be a martyr. People may think I'm hard but, to me, it's almost self-preservation. I tell myself I would be no use to him if I had a breakdown, which is probably what could happen if I couldn't get out like I do. He also goes into respite care for 6 weeks over the year. I know he doesn't like it as he obviously must miss the home comforts etc., but the good it does for me is immeasurable. The feeling of pure release I get when I'm driving back after dropping him off at the care home is amazing, but then of course the guilt kicks in and I start thinking what a hard cow I must be to leave him like that! But I know he is safe and is being looked after and that, for my survival, I must switch off and concentrate on me when I can. Booking a holiday is never easy. I only usually get a few weeks notice beforehand as to when the nursing home can take him, by which time trips I want to go on are booked and the dates aren't suitable for a friend to come with me, so I end up going away by myself. Not ideal, but I'm getting better at it every time I go.
Obviously, not knowing if you could leave your husband because of his mental state, things may well be very different for you. But there are quite a lot of clubs and things out there that you could perhaps join or get involved in with your husband. Try to do anything you can to get out of the house with or without him. It is so important for your own sanity. I know it may take a lot of arranging - getting someone to sit with him, or transport to get to a club etc.. There seems to be more clubs and organisations for people with dementia/mental health problems than not - at least that's what I found when I was trying to get my husband to go out. He, because he still has his faculties, doesn't really want to be mixing with people who have lost theirs. I can understand that, but sadly that's the main reason why he doesn't enjoy going into respite care as so many of the people there have dementia, which he finds depressing.
I recently started going to my local Carers' UK club which is excellent. There you will mix with people in a similar situation to yourself - I can't recommend it more highly. Everyone knows and understand what it's like and how difficult things can be because they are all in the same boat. The organisers are also very helpful and can give you info and put you in touch with all sorts of things. They also organise workshops and other events- the other week I went on one workshop on the subject of living with guilt. So see if you can start going to your local group - you never know, it could open up your life a bit.
You've already made a good start by posting on this site. We have to reach out to each other or else what will become of us? There are no quick answers - I can't imagine you'd walk out and leave your husband in the circumstances, but you may and if you did I, for one, certainly wouldn't blame you. You do everything you can for your husband, but it is vital you do the same for yourself. My thoughts are with you, real unhappiness is a dreadful thing to have to live with. God bless and be brave. x