Hi there

When I re-sided my house outside the bathroom window, I pulled on the
window too hard & cracked the grout between the marble tile and the
vinyl window. The window is in the SHOWER so is inherently a danger
for mold, rot, etc. (that's why I had to reside my house!). We will be
installing a shower curtain w/clips to keep water out of the window.
However, I have to replace the grout.

So far, I pulled out all the grout and caulk. It looked like someone
had mixed the grout with the caulk somehow (the caulk was very
discolored and thicker than plain caulk).

Now I'm trying to figure out my next step. Two days ago I installed a
layer of Silicon II caulk deep within the crack, thinking that might
provide an extra layer of sealing/protection if the grout fails. On
the sides of the window there is still about 3/8-1/2" depth for the
grout. On the flat horizontal surface, there is about 1/8-1/4" depth
remaining.

Was my layer of caulk a stupid idea? Should I rip out the caulking I
just put in? What's the best way to do this? The window is vinyl &
I'm worried the grout won't bond well to the vinyl, plus the window
will expand/contract since it's on the outside of the house, ultimately
cracking the grout. Either way, I'll seal the grout and then caulk the
joint between the window & the grout.

I've heard of epoxy grout--is this worth looking into? I read that it
doesn't require sealing.
Thanks for any help you can give me.
-Todd