The termination of your spousal maintenance obligation is specifically governed by the last final order in the case. Therefore, if in your last final order you have a cohabitation provision, the burden of proof is on you to prove cohabitation in order to terminate spousal maintenance. Often, this requires something more than your suspicion that this is happening. You will need to either conduct discovery or obtain a witness who can testify as to her cohabitation.
Any answer or response to your question I may provide does not establish or constitute an attorney-client relationship and is for general informational purposes only.
I recommend starting with the lawyer that handled your divorce. Tell them what is going on and ask what you need to do in order to terminate the payments. Take a copy of your decree with you (get a copy from the court if you no longer have it). The lawyer's copy may be in in storage by now.
Section 8.056 of the Texas Family Code discusses termination of spousal maintenance. Section 8.056(b) specifically discusses cohabitation of the obligee (the spouse receiving support) and provides that "after a hearing, the court shall order the termination of the maintenance obligation if the court finds that the obligee cohabits with another person with whom the obligee has a dating or romantic relationship in a permanent place of abode on a continuing basis." Translation: If your ex is shacking up with a boyfriend on a continuing basis--and I suspect 8 months qualifies--then she's not entitled to spousal support. Unless your divorce decree provides otherwise, I think you have a credible case for terminating your spousal support obligation. You will need to file a modification to bring these new facts to the court's attention.
Sign up to receive a 10-part series of useful information and legal advice about the divorce process.