I have always been ambivalent about Cole. He's not a terribly interesting character, and the "divorce" storyline, which had potential to reveal hidden depths, just made me angry.
Now, Cole has revealed himself to be such a dorknozzle (Old Wounds) that we find out he's been holding a grudge based on an imagined slight for years. It's just another example of lazy writing (SK: "Asshole." FSM: "Right, right...").
Why, in heaven's name, did it have to be like that? Would it have been so difficult to write it in such a way that she actually was was an old girlfriend, who just happened to start hanging out with Max after she broke up with Cole? That's an imagined slight that's believable.
(On a completely separate note, and I'm withholding judgment on this, but if this turns out to be a "look, we haz a gay now" storyline, I'm going to be pissed.)
So, Cole's an idiot, and were these real people, the level of hatred he holds for Max about an ex-non-girlfriend would clearly reflect on the state of his marriage in some way. (What ever happened with that? Oh yeah, nothing.)