After I file bankruptcy, is it safe to cash in my IRA that I have claimed exempt under Texas law?

No, not until (at least) the bankruptcy is over and closed. If you cash it in and don't roll it over into another IRA within 60 days, it becomes "non-exempt" and may be taken from you to pay your creditors. See In re Hawk, 5th Cir. 2017.
J Thomas Black
Board Certified, Consumer Bankruptcy Law- Texas Board of Legal Specialization