It sounds like you have a covenant not to compete question. Covenants not to compete in Texas must be reasonable in terms of scope, geographic area, and duration. Whether they comply depends on an analysis of your particular facts and circumstances. Also, a covenant not to compete must be ancillary to an otherwise enforceable agreement. This means that the company had to offer some independent consideration (value) for the covenant. Texas courts historically have been reluctant to validate a covenant not to compete, but have somewhat relaxed that position of late.
All that said, you would have to have an attorney read the covenant, and evaluate and assess your particular facts and circumstances.