family issues, sibling divorcing, advice needed!

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about 2 months ago my sister left her husband. I only found this out a few days ago, and with it I found out some pretty nasty stuff, and as much as I want to do something to my sister's husband for what hes done, my conscience is telling me it is not my place to be getting involved in their relationship and their current divorce proceedings. My sister's husband hit her, stole money from her inheritance...which she would of happily given him if he had asked but instead he stole it, and generally mistreated her. Now she has left because she, unlike so many people who end up stuck in situations like that, had the guts to stand up to him, and left. However what angers me is he is currently in possession of her car, going on a holiday that she booked in her name and paid for, and started spreading malicious rumours that she had an affair, which she did not. Should I try to do what my sister is doing and just cutting the ties because possessions don't matter and the fact that she is out of it and making a new life for herself is the important thing, or do I have every right to want revenge on this evil being?