I agree with another poster's comments. This was not an assault. Yes it was rude of him to throw water at you, and I have no clue why he did that, but I have to ask - why didn't you move away from the front of the stage after he had already thrusted his groin at you? That's what I would have done to avoid any further offensive interactions. But you stayed there, which likely gave him the impression it was Ok with you. And, you say here that you liked the attention so that's why you did not move. Honestly, you gave the wrong impression and made yourself vulnerable by staying in that spot.

Also, musicians are commonly like that. They will gesticulate in crude ways and that's all a part of the show and act. They want the female attention. Many musicians will assume if you are up front near them on the stage, that you want this kind of sexual attention, like a groupie would. He did assume, but you still remained standing there because of your crush, so you can't really place all the blame on him.