He would call any raise and go quite mental on the flop,
To be honest mate if this is the case then the guy's best avoided.
If there's a nutter on the table sometimes it's best to just fall in to place and let him take charge for a while. There's a long way to go yet and at some point you will pick up something better than J5 with which to do battle.
I went through a stage of making these kind of bluffs. You know the ones where in all likelyhood you are drawing dead. If you're going to war with this guy at least have some kind of gut shot or even bottom pair that could turn in to 2 pair. Anything to give a glimmer of hope if the bluff goes horribly wrong.
Call or raise him pre with some suited connectors then make your stand with either a pair or a gutshot with backdoor flush or something like that. Shoving with J5 here you were lucky to be in such good shape.
Yes his call was bad but you've already described him as a nutter so it's nice to have a bit of backup in case he calls with K high.
The bastard!!!!!!