The evidence that Henry killed her was she had flowers from Joe on her dresser. I think she loved Joe Wonty more than she loved Henry willy. The flowers on her dresser must have been given to her recently because they still look brand new.
She also had a picture of Joe Wonty on her vanity stand. She loves Joe and she wanted to keep him on her vanity because she thought that it was a good place to put them. The mirror on the vanity she could have seen herself get murdered.
She had a bandana around her neck, which means Henry could have strangled her with the bandana.