I feel so bad but I'm going to call the cops on my sister in law
Are you close to that side of the family?
We are some distant relatives. A while ago, some things happened in my family which I refuse to talk about more elaborately, but I felt like if it didn't come to call the police on this one, I wouldn't be able to live with myself anymore.
It is hard to do but sometimes in order to be supportive to your family, you have to do the right thing and help them when they need it. It will be more helpful in the long run rather than to stand by.
I want to serve my family
This is the best way to do it. Reach out for support after.