How to help a suicidal friend

Hello, so basically my friend has been depressed for while now, I tried to help him however I can but we can rarely see eachother, so we mostly just talk over discord. He was and still is seeing a therapist and taking antidepressants. Not too long ago his girlfriend of seven years broke up with him - they were forced into a long distance (which he also took very badly) and she couldn't handle it. Today we met up and he was unusually quiet, didn't really engage with conversations, mostly gave simple answers when we tried to talk to him. Before he left, he took me and our mutual friend away and said that he might try to kill himself in late july-early August, his family and his therapist know about it. We were really shoked, It's our first time dealing with something like this, we both want to help him, but we don't know what to do. The depressed guy us also exremely rational and seems to understand what is happening with him. He said that he doesn't want to do it, but he might get an impulse that he won't be able to resist. I would appreciate any advice on what to do, because I have no idea and I feel very useless.