RSUs causing extremely high tax exposure

Apologies in advance for yet another RSU question here.

I had $100,000 in RSUs vest last year. (Edit - 100k was the grant value) My company was fortunate and did well, and that stock was worth $500,000 when it vested.

My W2 shows $500,000 and my company withheld only 22%, so roughly 110,000. But ftusa now tells me I owe closer to 37%, i.e., $185,000.

  1. Am I really on the hook for $75,000?!! I have not sold any of my stock, so I don't have nearly as much in liquid cash.

  2. Shouldn't my W2 show $100,000? Isn't the stock increase capital gains and not taxed until I sell?

  3. Should I just give up and pay TurboTax 300$ to do my taxes for me? I'm having some sticker shock right now.

Thanks in advance!

Ps - numbers are appx.

Edit - Thx for the help everyone. It seems that I have the good kind of problem. I will now go scream into the void and sell my stock.