Hi catcuddler I don't think you are being fair to your current partner or yourself at all.
To be hankering after the Aussie ex and staying with him is wrong.
I don't think it's right staying with anyone just so you are not alone.
I personally think you should get yourself the help you need with your illness, then when you are stronger hopefully you will make the right choice because the person's right for you not just a crutch to lean on.
The Aussie couldn't have been right for you otherwise you wouldn't have got involved with your present guy.
As for present guy !"it's been good but we argue a lot as he's possessive and jealous" doesn't sound like a good relationship to me.
Give yourself a break, seek the help you need and don't settle for second best! we are all worth more than that.
New Year focus on YOU.
My best wishes to you for the future. x