Reserved :D
Was resignation necessary???????
He resigned because is losing more material and still under attack. If Qb7, just Nxf6 is going to lead to more material loss. After Bxf6 (or gxf6) the g7 pawn will be taken on f6 with check. If the queen is on b7, it also allows the queens to be forced off.
1...Qb7 2.Nxf6..Bxf6 3.Bxf6..gxf6 4.Qxf6+..Kh7 (if Kg8 then Qg6+ leads to taking on h6 with check) 5.Qxf7+..Qxf7 6.Bxf7.
That's probably not the strongest continuation, but even without an engine, it's clearly winning. Up 4 pawns, pieces active and black has 3 isolated pawns.
I think your opponent realized there was insuffucient compensation for the early exchange, also it is worth noting, you have a much more strong center than your opponent. It was still a playable position, perhaps additional exchanges would have hampered your opponents attacking potential a great deal too much.
Did he really have to resign????? He was 300 ELO points above me.
All criticism is appreciated :D