Rohde Game

This game was going well until I played 18.e5?

[Event "Thursday Night Tournament"][Site "Marshall Chess Club"][Date "2008.09.04"][Round "3"][White "Graham"][Black "Rohde"][Result "0-1"] [Opening "English opening"] [ECO "A30"] [NIC "EO.43"] 1. Nf3 Nf6 2. c4 c5 3. Nc3 b6 4. e4 d6 5. h3 Bb7 6. d3 g6 7. Be2 Bg7 8. O-O Nc6 9. Be3 a6 10. a4 Nd7 11. Qd2 Nd4 12. Rae1 h6 13. Nh2 e6 14. Bd1 g5 15.Bxd4 Bxd4 16. Ne2 Bg7 17. f4 Qf6 (diagram) 18. e5? (maybe 18.Nc3) dxe5 19. Ng4 Qg6 20. fxe5 Nxe5 0-1