Boiling Angst

I have question: I boiled my cup in a stainless steel pan. I left it for about more than 15 minutes. I don't think it melted (the shape is ok), but the pan now has a white "scar"/residue where the cup stayed on the bottom; and the cup is tacky, no longer smooth, but otherwise kept the shape and looks normal.

So, is the cup still safe? Does silicone give off toxins if it "melted" for a little while? Is the pan safe for use? Should I have used a telfon pan? Anyone had this problem before?