It is time for the talk. I don't have a child that age, but my little cousin lives with me and at the age of 14 he started acting out...this happen out of nowhere. And my grandma is rasing him, so she turns to me and wanted me to talk to him. I learned that something or someone can push him over the edge at times. Is he your oldest? If so, he needs to understand that everything he does can and will effect the family. Don't put too much pressure on him, but lay it down slowly that its just you three and your doing your best to act as both parents for him, but if you did something wrong (don't place blame on yourself, but see if perhaps something was said, done or not done). Of course, your mom, so some things are not going to be said to you and if you trust someone to talk to him, he may tell them and I hate to say it, but I got lucky because I am a hard core tomboy...so your son may need a male to look up to if his dad isn't around for that part. I don't know if this helps, but you have to remember, your son is older, experiencing more of lifestyle changes and social patterns, so talk to him like your son, but keep it the conversation as if he is an adult almost...not too much. It worked for me and I was just a kid when I did this...my cousin was actually bigger then most kids and he was being made fun of a lot and well, he got pissed off and took it out on other things because he knew hurting people was wrong. It took some time and a lot of talks, but we got through it and he found his group of friends, now in highschool and I still hang out with him. Good Luck.