That "crease" kinda has to be there. You can't wrap a piece of paper around a curved surface and expect it to stay flat. I have no idea what you mean by getting the vertices to align. Align with what? Do you mean you want them all on the same height? If so, you just need to snap them along the y-axis to whatever vertex you want them equal to. Do you mean you want them along a straight line? In that case, the best way would be to draw a new edge, cut it, and then snap your vertices to the new ones on that edge. Sorry if that's not helpful, but I don't really know what you're asking.
PS: I hope you know that model is going to be egregiously high-poly for that level of detail.