Defending against a "refuted" opening like the Jerome Gambit is easy - until it isn't. It is not good enough to just play the "right" moves. The followup moves also have to be correct. And the ones after those. Until you get to the playing level where people look at your game and mumble "and the rest is a matter of technique", you would be well advised to treat the Jerome with some seriousness.
Wall, Bill - Anonymous
lichess.org, 2019
1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+
4...Kxf7 5.Nxe5+ Nxe5 6.d4 Bxd4 7.Qxd4 d6
8.O-O Nf6 9.Nc3 Re8 10.Bg5 Kg8
We have an ordinary Jerome Gambit position: Black has a piece for a pawn, and has prudently castled-by-hand, while White has pressure on f6, and hopes to get his "Jerome pawns" rolling with f2-f4.
11.Nd5
An alternate was 11.f4, e.g. 11..c5 (or 11...Nc6 12.Qd3, as in Wall,Bill - Foman, Chess.com, 2010 [1-0, 22] or 12.Qa4 as in Wall,Bill - U80, PlayChess.com, 2016 [1-0, 29]) 12.Qd2 Nf7 13.Rae1 Bd7 14.e5 dxe5 15.fxe5 Rxe5 16.Rxe5 Nxe5 17.Qe1 Ng6 18.Nd5 Be8 19.c4 Bf7 20.Nxf6+ gxf6 21.Bxf6 Qd3 22.b3 Re8 23.Qf2 b6 24.Bb2 Qe3 25.Qxe3 Rxe3 26.Kf2 Re8 27.Rd1 Ne5 28.Bxe5 Rxe5 29.Rd7 a6 30.g4 b5 31.cxb5 axb5 32.a4 bxa4 33.bxa4 c4 34.Rd1 c3 35.Rc1 Rc5 36.Ke3 Bb3 37.Kd4 Rc4+ 38.Kd3 c2 39.a5 Rc5 40.a6 Ra5 41.Kc3 Ba4 42.Kc4 Rxa6 White resigned, Komodo 5 - Wall/Rybka, Florida, 2018.
11...Ned7
Overly cautious, perhaps anticipating f2-f4. Better was 11...Be6, as in Wall,Bill - Guest4809124, PlayChess.com, 2013 (0-1, 41).
Now, White gets to pull off a small tactic.
12.Qc4 Kh8 13.Nxc7 Rb8 14.Nxe8 Qxe8 15.Qc7 Ra8
White has a Rook and 2 pawns for 2 pieces. Stockfish 10 says that is plenty enough for a clear advantage, but there is still work to be done.
16.Rad1 Qxe4
Black cannot afford this pawn grab.
17.Rfe1 Qc6 18.Qd8+ Ng8 19.Re8 Ndf6
A slip, but defense was difficult.
20.Bxf6 gxf6 21.Qxf6 checkmate
Nice.