My mother's not alive anymore and I must admit to guiltily feeling relieved when she died. Not that I didn't love her, I did hugely, but she was a master of emotional blackmail and I never felt that I did what she expected either with my life or with things like presents, visits etc.
Now that I'm older I can see that she was driven by insecurity and loneliness and was probably depressed a lot of the time. She probably needed counselling but if it had been available, she probably wouldn't have known how to access or accept it anyway.
Having children of my own, I can see how it's possible to feel that you have given them more of your time, patience and love than they could ever imagine and to feel resentful if they don't, in some sense, repay that in kind. Young people these days have so many advantages and possibilities (I know they also have debts and worries, but so did we!) and I can see now how the parental generation might have also felt hard done by having survived WWII and having to live through a bleak 1950s.
However, on a one-to-one basis, I wonder if it's worth looking at a few books on techniques of assertiveness, the books by Anne Dickson used to be beacons. I wouldn't for a moment pretend that it's ever easy to deal with emotional blackmail but a few hints and tips about how to be clear where you stand and kindly but firmly maintaining that stance might make you feel better.
That said, I think I was a coward and simply avoided when I could and I'd probably do that now if she was alive. You have my sympathy.