All I remember is:
Justin left Pittsburgh and came back after a while engaged to a minister´s daughter. he walks in the diner with his girlfriend and everybody of the gang is shocked to see him. he just disappeared and they were worried about him. maybe it was after the bashing.
there had to be some trauma, because Justin didn´t remeber anybody from the gang, anything from his past or even that he was/is gay. At the end Brian and Justin are back together. I know it´s not much to go but one can always hope.
Thanks for your help,Sunny
It was found, many thanks to rusty1982:
How Can I Be Sure
http://www.ridiculouslyromantic.com/Fiction/HowCanIBeSureIChapter1.htm
And the Sequel:
http://www.ridiculouslyromantic.com/Fiction/HowCanIBeSureIIChapter1.htm