Not sure I have any advice as far as quitting and moving to FL goes, but I do feel your pain. My mom passed away almost 20 years ago and I've taken on responsibility for my grandparents, both of whom turn 98 next month. They're in Florida, I'm in Oregon.
She's been in a nursing home, pretty much flat on her back, for the last 4-5 years. She had a couple of surgeries and pretty much decided not to participate in the therapy that would have given her mobility back. Kudos to the folks at the home as she's healthy overall and mostly lucid. Just can't get around on her own and she's not willing to work on it. :(
He only went in about 18 months ago. He'd been driving, paying the bills, checking in on her, etc., but it was all taking a toll; each time I flew down he looked more bent and tired than the last time. We suspect he may have fallen at some point, as well. Dad (not his son, btw) had flown down to help him out, but needed to go home to Maine as my step-mom was having surgery. Day after I got there my grandfather ended up in the hospital (thought he was having a heart attack). Dehydration and some cracked ribs (maybe a vertebra too). After a week there he went into the same nursing home as my grandmother for rehab, recovered well, transferred to the long-term end and he's thrived. He can't live on his own, but he is able to get around without a walker or wheelchair all the time. They have separate, rooms, though, which is good because he can escape when she gets too feisty.
Biggest issue I've had lately is with Dept of Children & Families (DCF). They changed the patient liability (what I pay the nursing home from their retirement/ss) and I spent 3.5 hours on the phone with 5 agencies trying to find out why. Finally found out that they've switched to a new system and somehow lost track of the fact that I pay $400/mo for their dental insurance. ::eek Hopefully that will get cleared up soon. At least being in Florida you might get to talk to a real person.
If your parents are still in their own home (not clear from your post) don't be afraid to ask for help if you need it. In-home nursing, etc., is available under (medicare?). There are state agencies that can help with that, and despite my 5 agency run-around, I talked to some very nice people who really wanted to help.
Also, if they're still in their own home and you think you're going to have to put them in a facility at some point, with medicare, medicaid and all the rest, find a good lawyer who specializes in medicare/medicaid. I can recommend one in the Sanford area if that's near your folks. We spent about $2,500 and it was worth every penny. There were no questions or delays getting his paperwork handled as he transitioned out of rehab and into long term care; that would not have been the case if I'd have had to figure it all out myself, believe me.
A final word of advice, from a guy who's probably a bit younger than you.
Don't forget to take care of yourselves. Caring for your (grand)parents is mentally exhausting, doing so in person will be physically exhausting. Don't let it ruin your health or your marriage.