Question
We had a rare freeze in West Tx. in mid. Jan.(-6?. Our 35 yr. old flowering plum tree bloomed in April, but now the leaves have fallen off and the ones left on the tree are brittle,dry and pitted. The branches are also brittle, they can be cracked off by hand.  Has our tree died.

Answer
Sounds like it sorry! You can see if any of the branches are still alive by starting near the end of an upper outer branch and scrape a small bit of bark off and if the color under the bark is green the branch is still alive. If the color under the bran is brown the branch is dead at that point on the branch. IF not green continue down the branch scraping at intervals until you find green or reach the trunk. Try other branches until you find green. IF green is found you can either prune the dead wood off or wait and see if the tree will leaf out and then cut off what is dead. But based on you description I would not expect much. Sorry!