+1000 for what Angus said above. Get involved and get him help - don't be the only help he has - which is exactly what it sounds like you are trying to do.
As a professional, and living in Michigan, I wonder what area you live in. Your county will have resources that can help. Calling the local Community Mental Health Center for information should be really helpful. Depending on your friend's resources (insurance, finances) they should have a list of area providers, and also give advice on where and how to take your friend in for an evaluation. At the eval, they would determine what level of care would be most appropriate (inpatient, partial, outpatient) and help connect him to an appropriate therapist or treatment facility. Often, the social work staff at your county hospital (often working out of the ER, but not always) can do this eval and referral as well. It would be very helpful for you to know what options exist for him right now where you live, how you would best access them, and what to expect once he gets there. Keep him working on a plan that leads to him feeling better -from one day at a time to one minute at a time- whatever he needs right now. He also should know that it's really common for the brain chemistry to kind of get "stuck" when there has been too much stress for too long. With this being "stuck" comes certain symptoms that we sometimes label "depression" or "anxiety". We all can get these from time to time, and especially during times of prolonged stress. The thing is - when a person has this depression or anxiety - they come with a package of symptoms - depressed mood, sleep disturbance, eating disturbance, tense-restless feelings, difficulty concentrating, feelings of guilt, feelings of being punished, etc. Sometimes the suicidal thoughts and plans come in here as well. The bad part is having all these symptoms sucks. The good part, is when the depression and/or anxiety gets better, all these symptoms do too. All the negative thoughts and feelings he is having right now are a part of the package.
The good news is that this is very treatable. He just needs to get connected with the right person(s) right now to deliver that treatment until he is feeling better. Right now you need to keep him safe, get more information, and get him to the resources that will help him the most right now.
He's lucky to have good friends like you all. Good luck with this - I will keep you in my prayers and look to see how things are going if you choose to update us.