While I don't know the cause of the issue, and have never had it myself, the reason for the crashing upon login is due to your character being physically located in a dimension that is somehow bugged. Deleting the dimension folder would only mean your character is now in a dimension that does not exist, and the only way to fix this would be teleporting your character out.
How to retrieve your character:
1) You can use MCEdit to move your players location to the overworld(there are many fantastic tutorials out there)
2) You can maybe use NBT editor to change your location in your servers player.dat file. (don't know if player location is stored here though)
3) You can promote a trustworthy friend to OP, and as soon as they see you come online, use: /tp YOURNAME FRIENDSNAME
3a) They need to have the command pre-typed and ready to hit enter as soon as it says you're online, so the teleport happens before the server boots you again.
There are some other methods, 1 and 3 would be the easiest.