Makethepainstop he sounds like a bit of a tosser, judging your relationship with your exH like that. To me, that sounds like he was preparing to make a tactical withdrawal and was setting up the reasons for it during the conversation.
As far as dating sites go, I've looked at a few (I'm on DatingDirect, which uses the same profiles as Match I believe, it's just easier to say I'm on Match as everyone knows that one)
It's been okay for me, the 'daily 6' they send through each day are mostly rubbish. Too far away, too old, too young, too frighteningly scary.
I looked at datingforparents, and the profiles there seemed lower quality, although how you can tell I don't know.
Haven't tried MySingleFriend although people on here say it's got low numbers of guys in there. GuardianSoulmates might give you people more into your politics/world view if that's what you're into.
I think Eharmony, MatchAffinity, OKC etc which use special woo algorithms to match you up are rubbish. There's no validation to it at all, no piece of software can tell you whether there'll be chemistry or not. Only meeting someone can tell you that. And there will probably be quite a few dates with guys before you feel it.
I'd say go with Match, more likely to find people round your area. You can probably find more blokes with kids on there than you could on SingleParents.com (or whatever you're using)