"But he was married to one for nearly 20 years - do they generally hook up?"
First rule is take everything a person says about his ex with a grain of salt! Of course he is going to denigrate her, probably for not going along with his foot fetish. He's probably describing you the same way.
He obviously was "damaged" long before his "long, awful marriage"...I think you must relaize now how awful it was for her. Imagine marrying this man and THEN finding out his issues. She probably did her best under the circumstances.
Ignoring these kinds is the most effective response; even angry responses can sometimes encourage them, causing them to think there must be some interest there if you care enough to get mad. Ignore.