Oh Mikey, I'm so so sorry!!!
My husband and I were kind of in the same place, but not to the extent of you and wife, when we discovered our sons drug addiction. I took both of us going to alanon to be able to get on the same page. I was the one who said I could never throw our son out, no matter what he did, and in the end I was the one who did it. Fortunatley at that point husband and I were on the same page and were able to rally together and support each other.
I do believe your wife knows this is what has to happen, but it eases her guilt by putting the blame on you, which is totally unfair and will do so much harm to your marriage. It was the hardest thing I ever did in my life to throw my son out. I still remember standing there watching him pack, and he only had about an hours notice that he was leaving. I still remember standing in the front hallway and hugging him and telling him that I loved him with all my heart, but I couldn't continue to watch what he was doing to himself. If I could have, I would have loved to have put the blame on someone else as he walked out that door. In the end, it was the best thing we ever did for him, though we couldn't see that at the moment.
Your wife is worried about your son going to college and being successful, but she has to see it's not happening while he's living at home, so him leaving isn't going to make a bit of difference. You said he's skipping school all the time, so he probably won't even graduate highschool at this point, never mind go onto college, until he makes some choices, no matter where he is living.
I know you also see this, but your son is getting exactly what he wants. He is pitting you against his mother and he is winning. He's probably hoping that you will get so fed up with it, that you will move out and he'll be the one ending up staying causing chaos for the rest of the family.
I don't know what the answer to all of this is. I wish she could see where my son is now. Believe me, he's not living the life I dreamed of for him, but he is one year clean, healthy, happy, working full time, has his own apartment, and he's only 20. It was a long road for him, but one he never would have followed if we had allowed him to continue to live home and ruin all of our lives. The best thing is, he knows this and he thanks us for it. I hear him telling other people now that he didn't get it until he started listening to what everyone else was telling him and learned he didn't have all the answers.
We hope you keep posting. Don't ever feel you have to raise the white flag. We never say things so that we can say, we told you so. We say things from experience and things that we know have worked.