I’m very close to my sister. I overheard her being called a s@@@@@, f@@@@@@ c@@@ by her DH - and a door being slammed. Her 2 children froze as if they were used to it - and mentioned something about Daddy being mad again. I texted her to ask if she was ok - and she messaged back about a different subject. A day or so later I messaged that I loved her, and that I’m always there for her. What do I do?