I think my SIL has been lying to us

My SIL moved in last month to get back on her feet. My husband doesn't have a great relationship with his family. Both his parents were abusive. His sister is actually his half sister and she lived with her dad. She has stolen from him. Took out credit cards in his name. Fucked up his credit and he is wanting to forgive her and help her because she said her ex took full custody of the kids after she left him. She says he abused her and sex trafficked her. I was wondering how he got custody of the kids if he's so terrible and I know terrible people can manipulate the judge but an interesting thing is they have 2 kids together that are 8 and 2. And she has a teenage son with a different man. That man is a truck driver so he's gone a lot. Her ex was given guardianship of a child that is not biologically his. For him to gain custody of a child he has no rights to, to me that tells me she did something. My husband is easy to take advantage of. He has PTSD. Autism and bad abandonment issues. He just wants to help her but I feel like she's lying about everything including the abuse. Here's why:

Reason #1: She told us specifically her ex sex trafficked her. My husband and her were watching spit on your grave and she said if she was ever raped she would do the same thing. I told her "I thought you were sex trafficked?" First she tries to gaslight me by telling me she never said that. When my husband told her she did and she couldn't gaslight anymore she said what she meant by sex trafficking is he too explicit photos she sent him and used them to catfish men for money. That's not sex trafficking! Revenge porn maybe but that's not what sex trafficking is.

Reason #2: She is not trying at all to get any custody of her kids back. She has things she's supposed to do to get custody but she hasn't attended any classes or therapy. She will also only work under the table jobs because they gauge her wages for child support.

Reason #3: So she said the judge refused to listen to the pictures of bruises she had when she claimed abuse in court. My husband recently found out why that was denied. Or one of the reasons. Her ex has a picture of her YouTube history that was filled with videos on how to make a bruise with makeup. She said that was for something else.

Reason #4: Her story changes all the time. She said she left because he slapped her teenager across the face. But then when she missed court she tells my husband "I still plan on eventually getting custody back. Right now they're fine. He would never hurt them." But before you claimed he slapped your teenager across the face and now you're saying he wouldn't hurt them. Also I've seen her teenagers Facebook and he posts a lot with her ex who is his step dad and even talked about how he has 2 dads. Biological and step.

Reason #5: She lied to my husband recently about having AIDs. That her ex gave her HIV and that it's progressed into AIDs... In like a year. Yeah that was a lie and she tried to gaslight us saying she didn't say she had it. She said she thought she did. I'm over her.

She is not paying bills. She's leaching and honestly with how much she still lies I don't trust her not to steal from us or steal our identities again. I believe victims. Until you give me a reason not to and these are not even a majority of the reasons I think she's a liar