How can I maintain my own health when caregiving for a husband?

Need some me time. I run into this a lot with patients and their spouses. It is very important that the caregiver find some way to carve out some time on a regular basis to nourish themselves and attend to their own needs. Otherwise caregiver burnout occurs over time. Also you may want to look into what is called respite care. Some nursing homes will admit a patient for a week or two to give the caregiver a break.
With support. You have brought up an important question. Everyone caring for someone with a chronic illness needs to be diligent to take care of themselves so they can be an effective caregiver. You need to seek out support in the form of either direct help to give you breaks, someone to talk to for emotional support, help with chores or shopping. Whatever you need. Don't go it alone, get the help you need.
Balance Life. It is essential to keep your life in balance. For most caregivers it is important that they arrange to have literal distance from the person they care for at least weekly. Take a time out for yourself. Continue to engage in activities that give your life meaning & that you enjoy. Remember not to neglect your own needs. Don’t let being a caregiver be your only identity. Be willing to accept help.