Maybe text her 'how are you holding up?' Or 'hope all is well with you.' That way you don't feel guilty. Also, text her a song like 'brave' 'follow your arrow' or other cheerful things to make her smile. Text her jokes, keep it light. She might not be up for sad things if she's primary caretaker. See if you can do anything. Ask her if she's eating and sleeping regularly. And tell her it'll be ok and be open if she needs an ear/should to cry to/on.