For a start alcohol is a depressent so defeats the object of taking anti depressents. But anyway.. im 2month clean today from cocaine.. and cocaine made me want to commit suicide . Even in front of my gf which wasnt good.
Is he on coke? Sounds like he could be.
How old is he?
And what ever he is doing , he must want to quit on his own, because you will never make him. Id sit him down you and your mum, tell him it needs to stop and you aint bailing him out anymore unless he changes.