So I'm A Victim of Plagiarism

That is, someone published my unpublished work (and the work of some others) under other names, word-for-word.

Here's the story:

I was in on a paper project--a relatively minor project, a collaborative effort explaining several errors in a well-known critical thinking exam. The guy who ended up being the lead author on the paper was a real piece of work. What he produced was really terrible, and I and three other co-authors, including Johnny Quest (who made by far the best point in the whole paper) told him that we were splitting our project off, and that he couldn't use our work or our names. Although our group and the other group had noticed many of the same things, our group had identified more problems, and had expressed the problems far more clearly. So the lead author and three other authors--all of whom we know, and all of whom are scrupulously honest--split off from me and 2-3 other people. At the last minute, we discovered that the lead author had tried to publish the paper in a well-known philosophy journal with our names gone, but our work still in it. I had to call the editor and have it stopped. (The editor was actually so fed up with the lead author's shenanigans by that point that he blew up at me about it, saying that this was "the last straw." We had words.)

A year or so later, I put in a bunch of work on the paper, and kind of tried to get my co-authors to get it polished up, but it fell by the wayside and never got finished.

Recently, one of the co-authors wanted to finally get it out, and I told him to make sure to check the other paper that the other guys published. We didn't get any ideas from them, but I wanted to make sure that we footnoted any points that both groups made.

When we looked at the paper, it turns out that the lead author went ahead and used not only our ideas, but our actual words...though, of course, not our names.

The guy is such a loser that he ended up not having much of a career, but I'm going to pursue the matter anyway. He clearly plagiarized our work intentionally, with full knowledge of what he was doing. He tried to do it once before and we had to stop him. So he knew what he was doing.

Any advice on this would be welcome.