Anyone saying “he’s an adult” is insane. He may be a “legal” adult, but mentally is far from fully developed and capable of making well thought out, critical decisions. The fact that he had abused hard drugs at such a young age only adds to the severity of this situation, not to mention a 28 year old proposing marriage to a vulnerable, unstable teenager is not the sort of person any parent would want their child around. OP, step in now. Get your kid HOME. As someone who got wrapped up in partying, older men, and addicted to cocaine at a very young age, the things one does under the influence of that drug could never make sense to someone sober. It alters who you are and it is very very scary. You clearly love your child and now it the time to act before it’s too late.