I'm not familiar with this line. There's a hole at e5 but he's also opening up for an attack on the kingside.
5. cxd5
Not sure what the right continuation is here but the ideas from the QGD are no longer valid so I wanted to make sure I didn't lose a pawn.
5... exd5 6. Nf3e5
Maybe simple development here is better? I knew I wanted to get a piece on e5 at some point but I needed to finish my development first, I believe.
6... Ng8f6 7. Bc1g5
I think one reason I moved 6. Ne5 was that I hoped he'd bring his knight to f6 so I could get my black squared bishop out.
7... Bf8e7 8. e3
Mostly I'm following my understanding of Queen's Pawn openings here. Preparing for kingside castling.
8... O-O 9. Bf1d3 Nf6e4
I thought this was a good move for black.
10. Bg5xe7
forced
10... Qd8xe7 11. O-O Bc8e6 12. Qd1b3
? Stupid mistake immediately loses the exchange. I don't even know why I was so eager to get my Queen out there anyway. Be2 is better.
12... Ne4d2 13. Qb3c2
In addition to going down the exchange I now have to deal with a coordinated attack on my kingside with my pieces only partially developed. I should have lost from here.
13... Nd2xf1 14. Ra1xf1 Nb8d7 15. Ne5xd7
I didn't want to have to recapture with my d pawn and not be able to defend it. His kingside attack starts now.