Change it and ignore it!
Why not just get yourself another account - Yahoo again, if you must - and send out 'change of address' emails to anyone who needs to know? (Not your whole address book, 'cos it's quite possible the spam leak came from one of those in the first place.)
Then regard your new email addy as your principal one, and perhaps have a little look at the old one every so often, just incase anything important snuck in.
I was quite surprised at AOL. Stopped paying them nearly a year ago, but they haven't got round to killing my old email. Lots of unread and unwanted stuff still being sent there.... who cares?