Did I overreact? He dumped me.?

The guy had a lot of baggage. I get that you liked him a lot, but ultimately you will be doing yourself and your son a favor if you find someone not carrying so much. I suspect he has unresolved issues from his service in Iraq and never dealt with it, instead trying to numb it with alcohol. You will only regret your decision in 2-3 years IF he gets treatment and sorts out his issues. But look at it this way: you treating this behavior with the seriousness it deserves may, just may, tip him to finally getting the treatment he needs.