There are suicide hotlines (tons) and ER and anyone suicidal can get hrlp. They are trained to help suicidal people; we are not. It is better in my opinion he learn to uttilize outside sources with the proper training.
Often when they talk suicide to us it us a manipulation to get us to soften and do them a favor. But they wont be able to pull that with professionals.
You can quit using at any age. Young in my opinion is better. My daughter used from 12 to 19 then quit at a young age. They are not too young to know it is dangerous. They are well aware. They just dont care about themselves as much as we care about them and we cant make them.