I certainly get the gear itch, but having just picked up a 1DX after already owning the 5D3, I can very easily advise you to stick with the 5D3 and spend your money elsewhere. The 5D3 is a better wedding camera if only for the silent mode...the 1DX has nothing more to offer that you would actually use. Plus, the extra resolution of the 5D3 will be nice to have when you're making prints of portraits and such. The 1DX has better high ISO on paper, but when you compensate for the exposure difference, it's pretty much a toss-up.
The 85 f/1.2 is an exceptional lens, so not a bad investment at all -- performs quite well on the 5D3 to the point that speed shouldn't be factor against buying it. If you already own a 70-200 f/2.8 II, you may not find it gives you all that much more than you already have. The f-stops wider than 2.8 are so thin that you won't get an entire face in focus, so practical use for wedding portraits is a bit limited in that range. My next purchase is probably going to be the 8-15mm f/4L Fisheye -- I currently have no way to produce the type of images that lens will give me, which makes it very appealing. I've seen a lot of great wedding shots using the ultra-wide range and it would be a nice addition to the arsenal.