Keep in mind that once he is independent and successful he might never find a reason to return home, which might not be a bad thing for you but much harder for his father.

I was raised in a catholic household that I didn't agree with and my own mother had the nerve to kick me out of the house. I was 17 and although I did not have a job, I made nearly perfect grades and was never in trouble at school, senior year I got 3 different standout awards for my grades, test scores, and AP average being above a 4. I got caught smoking some pot and my mom and dad decided I wasn't fit to live in their house [mind you they never had any conversation about drugs or them being inappropriate], and they spread my actions throughout the whole family and told everyone; my family is all religious and I was humiliated. My mother never hit me, rarely used verbal abuse, but being kicked out of her household was the ultimate abandonment, it conveyed that I wasn't worth keeping around and that I was unwanted. I will never get over that feeling or rage, I hate my parents with every fiber of my being and my success is entirely motivated by the fact that one day I will hopefully have enough money to take everything from them. I sold drugs for 3 years, hussled my ass off saving money from that, put myself through a top university, graduated early, got a job, paid back all the taxes for the money I amassed through contraband, and it'll be a cold day in hell before I ever acknowledge my mother as something other than a random person. My parents tried to visit me once in college a few days before graduation and parked in my apartment complex. I answered the door, asked them what they wanted while calling them by their names, and slammed the door in their faces and got their car towed for violating parking, now they can know what it is like to be abandoned. Seeing my parents break down in that parking lot after abandoning me and kicking me out of their household was the most satisfying sight I've ever seen and I like to imagine the tears streamed their entire walk to the impound lot, and even that doesn't compare to the amount of crying I sustained through being thrown out, living on friend's couches until I had money saved for rent and a deposit, and regularly going without sleep or meals to take care of myself. The point of this isn't to make you scared, but to show you how anger is processed by a kid. More than likely he wouldn't even change his opinion of you, but his father...the one person who has been there...I can't imagine he'd recover from that, even if it is M's fault entirely.