I'm planning to help her move the body down to her basement.
Are you committing a crime by doing that?
You should think twice before you give me that kind of advice.
You need to get the police involved and let them know what is going on. You don't need to cover for anyone.
I'm trying to be part of her life.
She does not seem like someone that you should want to spend time with. You should not help her move a dead body.