Phoebe, you don't sound pathetic at all. It's very upsetting when a marriage is suffering, and the person you love is not with you. It's frightening when you don't know if you will be able to support your kids. I'm sorry your hurting right now, but it's only normal.
Remember this, what doesn't kill us, will make us stronger. Your husband really needs to work on himself and his drug problem, before he can be a good husband and father. It's sad but true. I sure hope his mother isn't enabling him. Do you think he ran there so he can use drugs and get over on his mom? You will have some ups and downs for a while, but you will heal from this. Just think of the poor wife that can't get her addict spouse out, while he continues to use and abuse in front of the children. This could be a blessing in disguise. You just can't see it yet. I hope everything turns out the way you want it to.