How do I get space from a clingy friend?

I have some stuff going on that I want to sort out in my life, but there's this online friend who always wants me to give them attention. One time I explained to them briefly what was going on in my life, and that I would like some space...then later that day he took an overdose on pills. Luckily, he went to a hospital and is fine.

He does this to people who become his friend and I just wish he knew that people don't always reply to messages within an instant. He sends me messages about people who don't reply to him within a few hours. I don't hate this guy or anything, but I have my own issues to deal with. I do make time for him...but there is only so much I can do when he rarely takes advice. I am there to listen, but sometimes I just need a day to myself.

As soon as he sees me online he sends me a message and I told him that I am signed in automatically (it's on a social program/app) and I don't like receiving messages as soon as I come online and he finds that amusing but continues the habit anyway.

I know I can just ignore it, but that one day I took some time for myself he ended up overdosing...so I really don't know what I can do. I have suggested to him to get psychological help but he doesn't want to.