Raise sink up off pedestal
Epoxy would work, though it would be troublesome to get in there.
If it was me and I knew that the sink would be trashed after a couple of years, I'd just support the lip, get a tube of normal white silicone caulk and start loading up the crack. Let it dry for 24 hours with the support in place and then you're good to go. (The silicone will compress a tiny bit, but not much.)