No Texas laws would be broken but many US laws would be. The Supreme Court ruled after the Civil War that secession is unconstitutional. What if the feds said, ok Texas, you can go but not another federal dollar goes to Texas including social security payments, welfare, military retirements, education funds, nothing! Could Texas take up the slack of it’s residents and others wanting to move there?
But that's my point--once Texas secedes, no US law is applicable, thus no laws have been broken. It's like trying to enforce US law on Somalia, when no equal law exists in Somalia.