Sorting out memories

I have moved out from my room and am currently residing in Shelley's guest room.
I have all my belonging here, and depending on how you see it, is taking over their garage, or it is really pitiful considering it is all I have from the 13 years of living in England.
How do you decide what needs to come home to Sweden straight away and what can come in 6 months or so?
How do you decide which of your memories are more important than others?
For me it is a heart breaking task and I wish that someone else could do it for me.
But Im putting my big girl pants on and getting on with it.
Or I will do later, must watch a film now.