Sorry guys, I just want to let off some steam in a place where I know people get it

I've posted about my sis leaving her husband recently. He is one of the 'control through threats and intimidation' brigade, much like my mum and step-dad. When my sis was married I didn't slag him off to her; as far as I'm concerned she's an adult and who she dates/marries/lives with whatever is her business and not mine. But I have always thought he treated her badly, I just kept it to myself.
Anyway, the police told him to stop hassling her and that if he contacted her again they'd arrest him, so he changed tactics and he's getting the kids to run messages to her. The eldest daughter, who I posted about the other day, is being vile and it's all coming from him, he's bought her a car and is giving her money; basically he's paying her to be a bitch to her mum. He took the younger boy's phone when he was asleep and sent vile text messages to my sister on that, so she thought it was her son saying things, and he's spreading rumours about the new chap and stopping her friends/work colleagues etc in the street to tell them things about her that aren't true.
He's texted me several times and I've just ignored him but yesterday I just lost the plot. I called him back and screamed and shouted so hard down the phone at him that I left myself with a sore throat and a headache. I called him every name under the sun and what I threatened to do to him if he contacted me again isn't printable. What made me so angry is that the cowardly piece of dirt backed down instantly and kept saying sorry, sorry, I won't do it again, He's so big and brave when he's intimidating people who are already scared of him but stand up to him and he crumbles. Moron.
Like so many of you, I find Christmas hard. It's a time for relaxing with family and being thankful for the people in your life. I don't have a family; I am related, either by birth or marriage, to a collection of people who are utterly selfish and have no positive or vibrant qualities about them. There is no one in my family I want to see or speak to; in fact, I never want to see or speak to any of them again. Like most of you, I get through the period by focusing on what I do have, keeping it quiet and just getting through it as best I can. I was so angry yesterday I was shaking by the time I got off the phone. I couldn't sleep last night and I've woken up this morning (it's Christmas Eve here) feeling sick and light headed (because I was too wound up to eat last night).
I am no longer going to be nice to people just for the sake of being nice; from now on people will have to show me that they have good qualities before I extend them my warmth and generosity. I am not going to keep my opinions to myself; I'm tired of thinking about other people's feelings all the time when so few of them think about mine. The best thing about yesterday is that I FOUND MY VOICE. I really let him have it both barrels and I am glad it was one of the few times I've actually been able to scream and shout and kick off at someone.
Thank you for reading all of that. I'm sorry it's so long. I feel better just for having written it down. Thank you to all of you for being there, and for understanding.