Lisa,
I am a caregiver for my Mom who has emphysema and COPD and my son who has a nuerological illness also of unknown etiology as well. I know how exhausting it can be doing that and neither of them are my partner so I can't imagine what that adds to your situation. I too think it is critical to manage time away from your responsibilities. I took a trip to WDW for the first time without either my Mom or my son in December. It was amazing how relaxed I felt when I returned. I think it will be great for your daughter too. I am sure your DH is nervous because you have done such a great job caring for him that he relies on you. But for you to continue doing that you need to rejuvinate yourself. And as you've said you have made great plans for an alternate caregiver while you will be gone. Your vacation plans sound perfect.
I agree with notion of mental escapes when you cant get the physical ones. I also surf these boards, take a nice hot bath(and splurge on some good bath soaps if you can), read, or just look at photos of other times I've gotten away and remember the feeling. It is physicaly,emotionally and spiritually draining at times to be a caregiver. I find even little things like making sure I get enough time to polish my toes or keep up my hair even make a big difference for me. Please do not feel guilty for taking time for yourself and your daughter. It is important to keeping you focused on all you have to do each day. Being a caregiver is a truly awesome responsibility and it is easy to get tired of it. Don't feel guilty!!! I wish you the best with everything and please also feel free to PM me if you need to talk. I am glad you posted this here. It is definitely the right place!