First of all, I know I'm BU and idiotic about this, but emotions aren't logical so please hear me out! Basically, I'm not keeping in regular touch with DF because talking to him can really upset me - and he's very angry with me.
My DF, now elderly and with increasing health problems, has always struggled with MH issues. I don't know the official diagnosis as he won't discuss it and Mum (deceased) never gave me the full details. She did mention manic depression, but I don't know if that's the full picture.
Growing up, Mum shielded me from a lot (and he was able to hold down a job) so I had no idea he made a suicide attempt when I was a young child - until things got out of hand when I was 13 and he was sectioned after another attempt. If a neighbour hadn't happened to stop by, I would have been the person who found him.
Anyway, when Mum died in my 20s, I suddenly became his emotional crutch and it was a huge shock, because his behaviour when upset (crying, ranting about things) wasn't at all what I expected. Mum had done an excellent job of supporting him all those years, so I didn't realise what he was really like.
I'd already moved to a different country, which was a big bone of contention...my Mum encouraged me in this move and I know think she was trying to protect me (not knowing she'd die early
). Luckily, he improved after a while and remarried my lovely SM.
She has no idea about his past and I know that his mood swings upset her, although he can also be lovely.
When I visit him, he can veer from being really nice to horrible and hyper-critical. This summer, even my DS (10) noticed that Grandpa can be nasty sometimes and didn't know what to think. Predictably, I've married a man who's the complete opposite, v. calm and stable. because that's the sort of Dad I want for my children. 
I'm "supposed" to ring my Dad every week (he expects it), but we had a stressful August (mainly DH's work) and I couldn't face talking to him. I have no idea what I'll get when I ring - nice Dad, grumpy Dad, miserable, "life is awful" Dad. Anyway, he rang recently v. angry and we had a short conversation as I was about to go out.
I know I need to keep in touch as he's my Dad and I do love him, but he doesn't seem to realise that I find it stressful (I have to psych myself up before calling) and that if things are rough here, I can't face him.
I don't know what to do right now. Should I ring and grovel (and get yelled at)? Should I be honest and say that when I'm stressed, I can't face phoning people - perhaps I should e-mail instead (he doesn't do texts)?
The truth is, he's not the sort of Dad I want, but I realise he's not going to change now.
Thanks for listening!