This is quite the story. I am very sorry that your friend hurt you, but I really think your friend needs HELP! He needs to go into rehab for his drinking and drug use. His actions might because he is hiding something, his feelings about being abandoned as a child might be catching up with him, someone he has been so close with his entire life is getting married and moving on he might feel he is also losing you also. So he has turned to alchol and drugs to fill that void he is feeling.
By his partner enabling his its not helping him in the least, he needs to learn to stand on his own two feet, but first and foremost he needs to love and respect himself and right now he isn't doing this,he is finding things (alochol and drugs) to make him "feel" no pain. He honstly needs help. I know none of this justifies they way he acted towards you because he was definently out of line and I am sure you don't need any of this right now in your life...but if you care for him still you need to talk to you him and let him know that you are there for him and find out why he is doing this to himself and his freinds/family. Because if he continues on this path nothing good is going to come of it...and watching people with additction is the hardest thing, and its something we may never fully understand.
I really hope things work out for you...and again I am so sorry to hear this.
Take Care