Aw Kathy, it is hard, I think these public holidays really rub salt into the wounds, particularly as we only tend to see and hear about happy families and obviously that makes it feel even worse.
I do understand the guilt. I remember sitting in a session with my T, in the days when I was still in contact with my mum, and I told her that every time I stood up to my mum (or just refused to do what she wanted or play the game) I felt like I was kicking a puppy. Even now I am aware that I'm really hoping she dies before my step dad because I know if he goes first I will find it very difficult not to reach out to her knowing she's on her own and grieving.
I don't know where the guilt comes from or how it gets there (or how to make it go away!). I've just done my best to ignore it and it has lessened over the years, but it still feels weird at Christmas, birthdays etc.
I do know what you mean about them not getting what it is you are trying to say. I spent years explaining to my mum how I felt about the things she did, how her behaviour made me feel, the effect all the things she did had on me and she just couldn't see it or accept it. Again, I don't know how, or why, but I do get what you mean about the frustration and disappointment when you try so hard to have a relationship with them and they just can't (or won't) change their behaviour to make that possible. It is soul destroying.
I don't know if manipulation is the only way they know how to communicate? They can't be direct and say "I'm sorry this has happened. I'd really like to try and have a relationship again. What do you think?" So instead they try and guilt trip you into doing things - indirect force, I suppose. My mum's sisters both think I should just forgive and forget, but what they don't seem to realise is that, even if I am able to forgive and forget (and I am getting there, slowly), I still don't want my mum in my life, because she hasn't changed and she will just keep doing the same damage. Other people don't seem to see that and it's hard to understand why.
I wish I had words of advice, it's kind of funny that after all of this stuff it's still impossible to put together a formula for recovery - do this, that and something else and you'll be fine. It's such a long and lonely road and I think things like Father's Day, Mother's Day, Christmas and so on bring up more problems to have to deal with and it's so exhausting. Perhaps we need an 'Argh! I don't want to celebrate my family!' Day or something like that

Anyway, Kathy, I do understand how you feel, it's a tough one to deal with, it's hard to watch people refuse to change even when you tell them clearly what they do hurts you. x