Spring, one of your sons is an adult and the other is nearly an adult. They know you are dealing with chronic pain, right? Do they know a lot about fibro? If not, educate them. There are several good things in Fibro 101 that you can print out and have them read. Then sit down with them and have a little discussion. Chronic pain is difficult enough and getting older adds to the mix. So, they need to start pitching in and helping you out and not expecting things to be the way they used to be...because they aren't! They definitely are plenty old enough to understand.
So, don't be hard on yourself. You have cared for them through all their illnesses and have been there for them through their school years so now it's their turn to help you! A big help would be not expecting you to continue to live up to their expectations. Just do what you can and don't blame yourself for what you can't do. People who don't have chronic pain can't keep up like they used to as they age. I'm not saying you are old but I couldn't do things in my thirties that I could do in my teens, etc. Just do your best, enjoy your life, and love your sons. Above all, be good to yourself.