If a person literally gives someone their password without any coercion or other trickery, then it's hardly hacking when they then use that password to access the other person's account. Leaving his password unchanged after dumping his digital wife is just plain stupidity on the hubby's part.
It wasn't much of a hack. She knew his login and his password. He should have changed it - his fault.
I think this is a serious serious overreaction. Her action is wrong because it was out of spite and she was acting to hurt him, but the fact it hurt him so much is also bad in a way. I don't go often but I can tell the difference between the real word and that of the internet. It is okay to be obsessive - but there is a point where an obsession becomes an addiction - once it is an addiction 'tis bad.