Sister deleted me out of blue from FB

[ASecretLemonadeDrinker]

Sister suddenly disowned mum because she rang her sister (so my sister and I's aunt) and said my sister was visiting Ireland soon (I guess implying she may visit?) and my sister blew up about how dare my mum say she was visiting people etc. She disowned my dad years ago because he went bankrupt and she'd "never been so embarrassed and ashamed in her life sob sob" when she went to get a contract mobile - which she was declined (well, my mum, sister was about 16/17) and this was pretty much how we found out I think, or he went bankrupt shortly after. Anyway, I hadn't heard from her since disowning my mum (about 2 months ago) so FB 'emailed' her and said we should meet up, I said I would find out when DH was working and I'd let her know. I was heavily pregnant, lots of problems - high risk downs/dwarfism, then breech etc. And I forgot. She emailed the next day to say how rude I was, I apologised about 5 times, she had another go at me, I said sorry again and that was it. She didn't acknowledge when I finally had DS3 4 weeks ago and tonight I have seen she has defriended me, and DH :(
WWYD? I am so scared of having my head bitten off, and TBH she is a selfish cow who needs a boot up her backside and I saw my mum pander to this for years and I can't be fucked TBH, but then I feel guilty...

You said sorry. She either accepts it or she doesn't.
Do you really need to keep in touch with her? If it was a friend rather than a family member would you have carried on trying and pandering?
She has her issues, let her deal with them

If you really want then send her one more message saying you've apoligised and if she can't accept it now then she knows where you are if she is ever ready to accept it. Your door is always open blah blah...

But if it were me I'd igore her.

Don't feel guilty.
It's very difficult.
I would be inclined to send one email telling her calmly you have had enough of her self centred behaviour. You would love a relationship with her but won't until she starts treating your family with respect. Finish by saying you will leave it up to her to get in contact.
She seems quite young, it may be a bit of tough love couple with a little maturity i what she needs.

She's 27 now, older than me. I'd love to tell her where to stick it, but I know I'd regret it. And I am a gibbering wreck with depression/anxiety and am too scared to open myself up to a nasty reply if I ask her whats wrong etc., I cried for ages and couldn't sleep (although conciously I brushed it off and told myself to forget about it, it was like subconciously I couldnt) when she sent me the nasty messages. But it's been 10 years since she even acknowledged my dad (2 or 3 of those were living in the same house!) so I know it's probably forever now.

My mum "I told you you should have contacted her". She even told me to ask her to be DS3s godmother to try and soothe her. She is DS1s and never bothers with him.

My brother is like this, I havent spoken to him for 3 years and much the better for it!