Welcome to SR and I'm sorry to hear what you are going through.
You need to stop hurting the people you care about. As addicts, we are really good at that. I hurt everyone that was important to me before my recovery finally started.
You need to take those drastic steps if this future with your husband matters as much as you say it does. Delete those accounts on the websites, delete phone numbers, get rid of the dealers for your coke, dump the booze, make it harder to give in to your vices then it is not to. Give yourself more time to talk yourself out of a decision.
Use your guilt as motivation to recover. I did, and I still do. I remember how awful I felt and I never want to feel that way again.
Everyone can get better. Everyone can change. It's time to make a plan and stick to it. And understand WHY. Why are you seeking sexual encounters outside of your husband? Why do you do the drugs and drink? What can you do to stop it?
Take time and browse through these forums if you haven't. SO MUCH wisdom here.
Good luck.