Supporting one another?

I was diagnosed with high functioning depression. It means excelling on the outside while being depressed on the inside.

My friend is bipolar and I've read lots of articles, books, and met with others experiencing mental health issues to teach myself because I'm the only one in the family with a mental health problem, and also to have a better understanding of bipolar.

We live far away from each other and I'm quite picky when it comes to choosing what I say to him, as far as he is now going through a major depressive episode.

I keep saying things like, "I care", "I understand", "im here for you if you need to talk", "it's not your fault", "it's okay", "you and your life matter to me" etc...

sometimes I get worried because he's just shutting himself down and cutting people off and taking forever to answer my messages, he also had a previous attempt to suicide that scares me more, I don't know if what I'm doing is good, or if it's bothering him but I really care. What do you suggest? what do you think?