Do you have some help and a support network for yourself? There are many people out there like you that can be a huge help as can professionals. Being a primary caregiver is and incredibly stressful thing especially if you have no support to talk or even give you days or hours off of being a caretaker. To do it alone without being able to talk will make a bad situation worse for you both. The stress you feel today can undermine your health and frankly nothing is worth your health.
You NEED a break, you DESERVE to be heard, you need to talk, have outside interests, and you need some help. You must resolve yourself to change some things to make life different for yourself or you both will suffer. Don't feel guilty about your very normal human reaction to your situation. Taking action gives you power and strength.
Living your life centered around someone else and their disease/disorder may seem noble or caring at one level but it is very stressful. Your entire system can suffer from constant adrenal stress which can cause all sorts of problems. I posted something earlier today about my mom being diagnosed with type 2 diabetes shortly after my dad's prostate cancer surgery. High stress in your life can come at a high price. Even your happiness is too high a price to pay.
In retrospect I was diagnosed with Parkinson's with things that were probably all due to an incredible amount of stress from an abusive marriage. I stayed too long and tried to work it out. My mom has a friend that was diagnosed with MS that found out she didn't have it once all the stress was gone from her life. The bad thing is that the long term effects can be permanent.
Your husband needs to understand in some respects too so that he can work to give you a break or some down time. He also needs to be aware how overwhelmed you feel at times. If you can find some help to have these conversations in a productive way with professional help or with advice from those that live with this situation it might make an incredible difference.
I lost a friend to Alzheimer's last year. His wife was his primary care taker and it was getting to the point that physical control to keep him in the house and safe was impossible. Her kids were all mad that she wanted to put him in a facility where he could be safe and not just leave in the middle of the night and disappear. One of the boys finally came and spend a day and night with him so she could go visit a relative and finally understood the difficulty that his much older mother must live with each day. It was a life altering experience for all of them. The act of finally understanding the incredible things she had to do each day was a changing event for their entire family.
I guess what I'm trying to say is be proactive and find a place to talk and get yourself a system to help support you. You might be surprised how much wonderful help is out there if you ask and poke around a bit. If there's not where you are then you may have to do a bit more work to set yourself up. Don't try to do this all alone. It's more than one person can do. I am so very sorry you have this burden. Just know that it can be better and you are not alone. Get past the guilt and know that deep down you need to be happy to be your best for yourself and your husband.