I'd be willing to bet that the death wobble set in first, THEN the TRE broke from all the rapid movement.
A buddy had nasty DW with his '04 Dodge 2500. He asked me to drive it to see what the problem was (he never heard of DW before, just told me the front wobbled bad on bumps) so we hit I-25 south from Dry Creek and there was a nice expansion joint at the top of the ramp. We hit that and I've never experienced DW like that before - I guess the difference in the size of everything the Dodge has compared to the XJ... well, that's a whole lotta mass moving around. It had the doors slapping the tops of the sills, and headed straight for the jersey wall. His factory track bar was bent at the lower of the two bends after that.
Sounds like you need to get it aligned by a shop that knows how to work with lift kits so that don't happen again.