Hm. That is one for the lawyers to debate. After all - he broke the relationship first, you two separated and were on the road to divorce. Unless you to did not separate, then it becomes an 'interesting' case.

First...why did you tell him? If only he had cheated, then yes you could file on the grounds of adultery. But since you technically did too...I don't know. Here are the Texas grounds for divorce. You'll probably have to go for the "no fault". Grounds for Filing: The Petition for Divorce must declare the appropriate Texas grounds upon which the divorce is being sought. The appropriate lawful ground will be that which the parties agree upon and can substantiate, or that which the filing spouse desires to prove to the court. The divorce grounds are as follows: NO FAULT. On the petition of either party to a marriage, the court may grant a divorce without regard to fault if the marriage has become insupportable because of discord or conflict of personalities that destroys the legitimate ends of the marital relationship and prevents any reasonable expectation of reconciliation. CRUELTY. The court may grant a divorce in favor of one spouse if the other spouse is guilty of cruel treatment toward the complaining spouse of a nature that renders further living together insupportable. ADULTERY. The court may grant a divorce in favor of one spouse if the other spouse has committed adultery. CONVICTION OF FELONY. (a) The court may grant a divorce in favor of one spouse if during the marriage the other spouse: (1) has been convicted of a felony; (2) has been imprisoned for at least one year in the state penitentiary, a federal penitentiary, or the penitentiary of another state; and (3) has not been pardoned. (b) The court may not grant a divorce under this section against a spouse who was convicted on the testimony of the other spouse. ABANDONMENT. The court may grant a divorce in favor of one spouse if the other spouse: (1) left the complaining spouse with the intention of abandonment; and (2) remained away for at least one year. LIVING APART. The court may grant a divorce in favor of either spouse if the spouses have lived apart without cohabitation for at least three years. CONFINEMENT IN MENTAL HOSPITAL. The court may grant a divorce in favor of one spouse if at the time the suit isfiled: (1) the other spouse has been confined in a state mental hospital or private mental hospital, as defined in Section 571.003, Health and Safety Code, in this state or another state for at least three years; and (2) it appears that the hospitalized spouse's mental disorder is of such a degree and nature that adjustment is unlikely or that, if adjustment occurs, a relapse is probable. (Texas Code - Family Code - Chapters: 6.001-6.007)