I never felt guilty for being happy because it was the only real revenge I ever got on my NM. She had tried very hard to keep me living in poverty. That was to be my punishment for not following the path she had chosen for me. I was the only child of the three who was not given help with college tuition, housing, anything. Everything I ever got, I got through incredible hard work, so I could be proud of myself for finally getting an advanced degree, a good job, and a nice home. M went into a rage whenever I got something that I "wasn't supposed to have." I never let her see that I was suffering inside from her cruel words, so all she saw was someone who had defied her, and gotten "stuff," and it enraged her. Living well and being happy was the only way that I could truly get back at her for the things she did to me, so I didn't feel guilt for it.
That said, I do have feelings of guilt over my decision not to visit her before she dies, and I shouldn't. If I were the one who had terminal cancer, I wouldn't get so much as a card from her. Yet it's very hard to turn off the guilt of basically abandoning her in her final months. I have to work towards shaking that guilt off, because she abandoned me decades ago (literally, as I've been given the "silent treatment" over and over, sometimes for years on end). It's a stinky deal. I was abused so badly, yet sit here saying, "but she's still my mother." But then, her method of attack from day one was to guilt me for "hurting her," so some of my feelings may be a little bit of brainwashing that I need to shake out of my head. You know, when someone spends 40 years telling you that you're ugly, or fat, or whatever, it's pretty hard to not believe it, even if just a little. I guess that's how brainwashing works. They repeatedly pound it into your head until it sticks. The trick is getting it out.