OK desolate, I'm not your big sister, but I'm going to assume the role for a moment, cos you need some straight talking again..
Unless what you have left there is of immense value to you, you NEED to walk away and give it all up.
TBH, I'd not want to leave keys with you after all of this to go through my house while I wasn't there.
Sorry to say, but you really kind of have brought this on yourself, if you'd have left before, when he was actually in the hotel, you'd have saved yourself all of this anguish. You didn't, so you didn't IYKWIM..
I think his new GF reaction is awful, beyond out of line and wholly inappropriate... but you don't know what he's told her. Wake up call time here though: Don't ever put yourself in the situation where she can do that again.
Change your number, change your email, make sure that he or she can't contact you - except through your solicitor.
Can you request that any items that are NOT his are delivered on his leaving date to your solicitor?
This has been a horrific situation for everyone involved, and one that shouldn't have been so needlessly painful.
NOW.. time to fill up your life with other stuff, join a gym, get a hobby, look up your friends, anything and everything to make you feel good about yourself, and to help you realise that it's over with Neil, that he's moved on and that you need to too.
2010 is the year you find yourself and forget about Neil. Time to turn the page, close the book, and start your new journey of discovery.
Please, just let GO! It'll be OK, but it'll never get any better while you are still clinging to the past. Wishing you well and looking forward to hearing all about your journey of discovery this year... and NO MORE ABOUT NEIL.... Let this thread die, it's time.