When bad felting happens to (reasonably) good people

This was going to be the post in which I showed off my newly finished, lovely sweater for this autumn. I've been working on it on and off for nearly a year: 4ply Swedish pure wool in a very scandinavian choice of 3 greys with occasional green and mustard stripes, all in garter stitch in an unusual construction. I'd done all the knitting and edging and found it hard to take it off whenever I tried it on, it was so cosy. All that was left to do was to run it in the machine just to full it out a little and shrink it a touch as all that garter stitch was showing sign of stretching well beyond the end of my arms.
It's not the first time I've put knitted garments in the machine and they have all come out magically improved for it.
Not this time.
Oh no.
I'm not sure what I did differently - I remember hesitating a minute before putting soap in - but what came out was very stiff, half inch thick, solid felt....about 1/3 of the size of what had gone in. This was not slightly shrunk in need of a good stretch. This was beyond all salvation unless I could find a five year old that wanted a jacket they wouldn't be able to bend their arms in.

I've done all kinds of bodging and rescuing projects before, but never messed something up so badly that it was completely unusable. There were tears, I'm not afraid to admit.  There was a lot of swearing. And then I turned around and saw this:

The thing wasn't even dry yet, but the thick wooly felt was just too much for one little kitty to resist.
So there we are. I didn't get a new sweater for work tomorrow, but apparently, this is the best thing I have ever made ever in the whole universe.

Pictures taken  within 10 seconds of my attaching the last thread - he was sitting on the table watching me with a "is it ready yet?" look on his face.