Honestly @SarahC50 that might have been the nudge you needed to realise now is the time to start focusing on yourself, your life, your needs, desires, priorities, interests etc.
I made myself do stuff last year - I went on holiday on my own, went on a retreat on my own, DH wasn't interested and DC were at uni. I didn't exactly enjoy either of those experiences at the time but they definitely helped shift my mindset away from 'how can I endlessly serve DC' to 'They don't need me as much any more. I need to think what I want to do with my life.'
You could do worse than make a list of things you want to do - a bucket list if you like - of anything from tiny things to huge ones and make a pledge to check off at least one a week for the next 52 weeks!
I am getting better at putting myself first. I had agonising shoulder tension before Christmas. Before, I'd just have taken painkillers and carried on, but I started a Christmas shopping expedition by spontaneously walking into a massage place and got a 1 hour hot stone and shoulder massage. I'd never before have given myself that amount of time or money, unplanned. It was instinctive too. I just thought, do it now instead of wanting it but ignoring my own wants, like a martyr, as I usually do.
No one asks us to be martyrs and no one appreciates it either. We end up resentful. They end up bemused or annoyed.
It sounds from your post like you really do deserve to do some things for yourself. What would you like to do?