How do I handle this? Depression

My man deals with depression. Being quarantined is really starting to get to him. Sometimes he won’t talk to me for a whole day, he says his thoughts are really overwhelming in his mind. This just happened, and sorry for my cringe texts but I was trying to lighten the mood.

I have never talked to someone who battles depression before. What are some things I can say in the future? How do I know when to stop talking or give him space? Or do I not give him space and keep the conversation going?