I've wanted this lens for years myself, so I think that I understand your predicament. I can also relate to your situation, although I'm a little older and a little better positioned - I have saved the money to buy this lens cash if I so desire - rather than putting that money towards the mortgage or new car or furniture or...
Anyways, after a full frame body, it's the final stage of my photographic needs & wants, as a gear knob amatuer.
There has been some extremely good advice in this thread about taking that money and investing in some manner instead of spending it. From experience, I cannot argue with that.
But - hey, some people in my neighbourhood put their money towards large boats or a cottage. In past, I've spent lots of money on rock climbing, adventure racing, sports gear, etc. You only live once and you don't know what tomorrow brings.
But - then, back to fiscal responsibility...
However, I looked through your excellent pictures, and I read through your reasoning. I think you seem to have a fairly good handle on advice, and your alternatives, wants, and needs.