The Doctors are all incarnations of the same person. River is married to that person, not to one specific incarnation only. However, she didn't marry him until he was in the incarnation we know as the Eleventh Doctor, so incarnations earlier than that -- & the Eleventh Doctor earlier in his own timeline than "The Wedding of River Song" -- were not yet married to her.
Thus far (before Series 10), the incarnations we've seen who were married to her -- that is, who were later in the Doctor's timeline than "The Wedding of River Song" -- are the Eleventh & Twelfth Doctors.
Also, we do not know enough about the laws & customs that (as far as River & the Doctor are concerned) govern the marriage to know what events or conditions might bring the marriage to an end. Therefore, all we can say for sure is that both the the Eleventh & Twelfth Doctors have shown that they regard themselves as married to River & that River appears to agree with them about that. She does not, however, appear to regard this as preventing her from marrying others, as we saw in "The Husbands of River Song".