depends on the illness/issues to some degree but the best help you can get for you is some individual counselling.
you can also ger referred for family therapy where the issues can be addressed as a family, and strategies agreed.
on a basic level, getting respite from caring for the person (sometimes jsut getting a break from being around a person's illnes) is essential - whether that is the person with MH going to friends/relatives for a break or the rest of the family going elsewhere for a break.
if children involved, very important they have time away - ask about support for child carers.
but depends on the actual issues to some degree as to what would apply, how frequently and so on.
carers org uk
www.carers.org/