I do appreciate everyone's comments on here. It's really interesting reading all perspectives, as that's what I was looking for.
I can see why some people are perplexed by my stance/reaction in this instance. I think that's because I haven't detailed the relationship history as it's too long and complex.
And yet, it feels weird to have my parents referred to as 'abusers' because there isn't really one particular "really bad" thing they've done and it feels a bit of a slight on them but more so on people who have been physically abused or whose parents have been really neglectful or have harmed them. But I do feel there's a lot of manipulation, a lot of expectation and a lot of living vicariously through me and looking to me to provide their happiness/life as they don't have that. I've spent the majority of my life trying to make them happy/keep the peace and give them a distraction from their unhappy marriage.
As a wife and mother I can't give them as much attention now and I think this is a huge thing for them. My mum shows no empathy when I talk about being so busy with full time job, kids, husband who works away a bit - she just says it was harder for her and makes comments like "it's ok for you in your big house" or "must be nice to have a man that makes dinner, I never had that" or tells me how stressed out SHE is living with my dad. (I have offered her help in recent times to break away, but they never will as both are completely obsessed with how things look to other people on the outside - this seems to matter more than how family members are really feeling).
Their marriage is unhappy and I've grown up walking on eggshells to try so hard not to rock the boat so they won't fall out. I've seen a lot of rows and some 'mild' violence, which isn't acceptable, but again feel like - or have been made to believe - that it isn't THAT bad.
My dad hasn't spoken to me this year; we spent NYE at my DS and I texted happy new year on NYE. My mum replied the next day, my dad read it and didn't reply. Mum did call on Friday to ask when she could see the kids and to ask what was wrong?! She seems to always 'forget' that something major and hurtful happened and can't talk about it and instead denies any knowledge of what happened.
I understand the people saying that it just needs to be talked through. I've tried this several times - explained how I see the situation and how it makes me feel and what could we do to help them and fix things and move on; this never plays out in a mature, calm and rational way. I don't think they're willing or capable of any self awareness/self reflection or to accept any bit of accountability.
Neither DF nor DM speak to their siblings, which is telling in that - they feel slighted by something (always) and can't talk it through and cut the people off then say nobody cuts them any slack or appreciated what they do for them. This is what dad's done with me now - with him not speaking to or contacting me yet this year. He'll be content to think it's all my fault ams I've driven him to this. But he's the parent here.
Sorry - too long again. But thanks for your insight.