I can see this situation from both sides of the coin. As a child I've been surrounded by people with serious mental health issues, it was exhausting and really emotionally draining and quite scary - it really changes you and your relationships in a way that is hard for people to understand.
As a result I then had a large breakdown in adult hood which my husband had to support me through and I know he struggled with this - I felt like such a burden to him and hated needing so much support. Unfortunately the breakdown led to lots of health problems and chronic illness, as my body couldn't take the stress anymore and I'm in recovery from those issues now but still affected by them daily in a physical way unfortunately.
I hate the impact this has had on my husband and the support he has had to provide me.
I became very aware that I have to find other sources of support to help me through this rather than just my husband as it is such a lot for one person to cope with when we naturally turn to our spouses for that main support, but I try to be mindful that he shouldn't always be the only person that is there for me!
I did however get quite hurt and resentful towards him (rightly or wrongly) when I could feel that it was too much for him to cope with or that he was treating me differently as a coping mechanism for himself.
Although I have lots of friends, I find it hard to trust others with my issues but have slowly built a small friendship group of people I can talk to openly, I try to not just go to one person for all my support now as I understand it can cause emotional burnout to over rely on one person.
These small changes have really helped the dynamics between my husband and I, and I have consciously chosen my battles of what I think he and I can or cannot deal with together, and gone to my other sources of support when I sense it's too much for our relationship at that moment.
Some people may say there's something wrong in our relationship for me to have to do this, but I'm very aware from being on the receiving end of being a carer that it is HARD for all parties to cope with and I want to also have a healthy relationship where there aren't resentments building.
Over the years I've also become a carer to my almost adult daughter and the burn out is real - it CAN affect the dynamics of a relationship if not dealt with purposefully.
I don't know how your husband can reach this mindset for himself OP, but please be aware that some people don't have the skills of resilience - particularly if they've had some challenges in childhood.
I've worked hard to build my resilience which wasn't nurtured in me from childhood, done lots of courses, counselling, research for myself because I want to be healthier /happier/a stronger person - but when I was in the thick of it, my mindset wasn't so strong and I REALLY needed my loved ones to be there for me, as much as I hated relying on people and being a burden to them.
Make sure you've got good people around you that you can talk to for some relief for yourself - perhaps a therapist for yourself that you could vent to once a month about the emotional burden you're feeling? I know this is something I think would be useful for me in relation to my caring role for my daughter.
And just remember that ill health physically or mentally can hit any one of us at any time - so give the love and care that you would wish to receive if it were you.
Chronic illness alone is a beast to battle with and can cause depression and hopelessness for one self, it can be hard to see the woods for the trees when you're in the thick of those health battles on a daily basis.
Hopefully this won't be forever and hopefully your husband finds some ways to build some independent strength/coping skills in the near future, it's OK to say you're burn out from it - you're only one person! but always keep kindness at the core of your actions ❤️