Hello, I'd like to help you with your question.
There are two possibilities here. One, your friend has a personality disorder such as Borderline where the person is attention seeking all the time. Often a person with Borderline disorder will do anything to get attention, even threaten suicide. And your friend's willingness to shut you out of his life when you did
share his suicidal thoughts with others also fits the borderline profile.
Another possibility is that your friend is really suicidal and is just working up the courage to hurt himself.
No matter which issue your friend has, you don't want to be the one to carry the burden if he does decide to follow through. At this point, you certainly have enough to file a 302. And your willingness to put your own need to be his friend aside in order to get him help and for his safety is admirable.
To file a 302, which is an legal document ordering an involuntary commitment for inpatient mental health treatment, you can contact your local ER. They will provide instructions on how to file the 302 and either have you transport your friend to the ER for an evaluation, or they will send the police to escort him if he is not willing to go. The person seeing the behavior must be the one to file so that would be you. Your friend would be committed for a period of time, usually 72 hours then his case would be re evaluated by the doctors and courts. They can either keep him for a longer time or release him for follow up with a local treatment center.
Here are some other resources to help you with ideas on how to help your friend:
I Am Not Sick I Don't Need Help: How to Help Someone with Mental Illness Accept Treatment-Xavier Amador.
Another option is to see if your friend is willing to see his doctor. If so, then you can contact the doctor ahead of time and let them know what you are seeing with your friend's behavior. The doctor is a mandatory reporter which means if he/she hears your friend's suicidal threats, they can admit him immediately.
I hope this has helped you,