Hello first of all, hope you're all well

Ok - I'll try to make this as short as possible...
My sister is 32 (I'm 22 and live at home with parents, I work full time, and I'm in a long term relationship of 6 years). My sister has been in an abusive relationship with the same man for about 15 years (abuse both ways) and at a time she would only come here when he kicked her out or hit her etc. She has 3 sons, one is 18, one is 16, and the other one is about 9 (but he was giving up for adoption last year due to my sister going into sheltered accommodation).
This is where the problems began, we took in the 16 year old for over a year, and she never paid a penny towards his upkeep, neither did the dad, we gave him clothes etc, paid for school trips, bought him a mobile phone and christmas presents etc, eventually things started going missing around the house (namely my PS3 games, DVD's, cigarettes etc) he denied taking them but was caught in the act, so we sent him back to his parents (by this time my sister and her boyfriend are back together). The oldest nephew is on drugs and has supposedly been diagnosed with a mental problem due to the drug use, he attacked my mam and swore and spit at her etc, and has been harassing my parents on and off for over a year. He has damaged the family car, and he was caught telling one of his friends to bang on our windows at night (neighbors caught him) and various other things. Basically we have cut them all out of our lives now, sister has never worked nor does her boyfriend and they live off benefits and have no intent to work,ever.
The other side of this is, I feel in a way this is holding me back as I'm afraid if I leave or move out, something could happen to my parents due to my sister/nephews, my dad isn't in great health and they should be able to enjoy their lives without feeling as though something is going to happen every day. Talking to them (sister etc) as you can imagine is a waste of time.
This is just a load off my mind being able to talk about it to other people, has anyone else gone through similar events, or any advice etc?
Thanks guys.
Re: Nephew/Sister problems (Longish story)
And I guess they like DUIs, unsafe driving charges, moving violations and whatever else that goes with it. I will bet you they gladly paid the insurance and registration and gas money, too, thrown in for all of his hard decent efforts at home!
Get away from them and TODAY.
And a therapist FOR YOU ---- you have a mess on your hands, too. I will bet also your sis is under the influence, also --- that's my sneaking suspicion.
And 32 minus 18 is FOURTEEN.
Where the eff were your parents when it was time to talk to her about safe and responsible sex and sex ONLY with the right person and using protection????
She went out and hatched out one kid minus marriage (and minus a high school "career," too!) and then did the same with 2 more kids. Isn't this great.
I am hoping she has at least a chastity belt, at this point in her stellar career.
You come from a nutty little household there, kiddo. My sympathies.
Cut all of them off today and without fail. This is a dreadfully unhealthy and unstable atmosphere and don't get embroiled in any of this mess.
Move out and get an apartment by yourself or with roommates, NOT move in with your boyfriend.
You need to date around --- I guarantee you you will marry this guy for all the wrong reasons. I don't want to hear "oh but I love him" or "no we are not like that". Nope --- date around, get a single girl apartment and cut this toxic and horrid bunch off for good.
Never contact them again. Do not even leave a forwarding address; let you rmother and father figure this shit out for themselves. You cannot fix what is wrong; this is a mess hopelessly beyond repair.
Chronically hilarious - you'll split your stitches!
I wrote a book! Bucket list CHECK!
http://notesfortheirtherapist.blogspot.co.uk