I'm wondering if anyone has been through this?

My mum has a brain tumour and can't do most things for herself these days, my dad does 80% of cooking and cleaning in their house, he works 40 hours a week, is self employed and can't afford not to work, he's so angry and depressed it seems these days, he does so much and is constantly looking after my mum, the house, cooking and going to her hospital / chemo appointments when he isn't working full time, he's also very upset his quality of life is affected as him and my mum loved their holidays and nights out having dinner and drinks before and now they can't do that as my mum is very slow to walk, can't walk far without getting tired and sore, is sick quite a lot with treatment etc and it isn't going to get better as this has been 3 years now, the tumour shrinks, comes back, and she goes through treatment again, on and off for 3 years, my dad is upset he won't get a holiday again, he can't enjoy date nights with my mum and all the things he does that makes him so tired as her carer and full time worker, he won't talk to anyone, it's obvious to me and my siblings he's depressed but he says he doesn't believe in therapy so he just rants to us, he said no one can make his life better as this is how things are so he has to get on with it so there's no point talking about it, he has outbursts every now and then when he tells us how upsetting it is and how he misses his old life, does anyone have similar experiences? I feel so bad for him even though our mum is the one with cancer!