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I'm sorry to hear about your situation. Assuming that there's a written spousal maintenance order that specifies that you have to pay maintenance for a specific period of time or that it ends upon a certain event, if the time period or the event has not occurred, you would still have to pay. Under the law it does not automatically terminate, but it could terminate upon a finding of cohabitation:
Family Code Sec. 8.056. TERMINATION. (a) The obligation to pay future maintenance terminates on the death of either party or on the remarriage of the obligee.
(b) 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.
(c) Termination of the maintenance obligation does not terminate the obligation to pay any maintenance that accrued before the date of termination, whether as a result of death or remarriage under Subsection (a) or a court order under Subsection (b).
Note that this is "after a hearing", meaning that you would need to file for a modification of the support order, serve notice on the other party and have a hearing to determine this fact. After that, the court can enter a new order that relieves you of that obligation to pay. But until then, you're still going to have to pay.
Hope that clears things up a bit. If you have any other questions, please let me know. If not, and you have not yet, please rate my answer AND press the "submit" button, if applicable. Please note that I don't get any credit for the time and effort that I spent on this answer unless and until you rate it positively (3 or more stars). Thank you, ***** ***** luck to you!