Madgran77
*The suit may have been the straw that broke the camel's back, given the difficult relationship you had with him before then*
I really can't get my head around this. I accept that there had been difficulties previously. However his dad wanting to HIRE a suit in the requested colour rather than BUY one... that really is a very flimsy straw and a very weak camel whatever had gone before!!
Anyway Elless I am sure you will consider the point, or probably have done already, and will draw your own conclusions. 
Maybe he didn't just want blue suits, maybe they were all going to have identical blue suits. I've known weddings like that, groom, best man, father of the bride/groom all in the same suits and ties. It could have been a misunderstanding where the father thought he was being reasonable and son thought he was being awkward about buying the same suit as the others. I think misunderstandings like this often causes upsets that seem way over the top.
On a positive note my GS who is estranged from his mother and living with me has had a wonderful start back in sixth form. I was worried it might unsettle him but the feedback has been better than I dared hope.