Praise be to Allah.
If the husband says to his wife: If you contact so-and-so, then you are divorced, and he intends divorce, then this is a divorce that depends on the condition. If the wife gets in touch with that person then one revocable divorce has taken place, and the husband may take his wife back so long as she is still in ‘iddah.
Does he have the right to cancel that condition and allow his wife to get in touch with that person in the future?
The answer is yes, because the divorce became effective with the first contact, and the fuqaha’ differentiate between the husband saying “if you get in touch you are divorced”, and his saying “every time you get in touch you are divorced.” The first form cannot be taken as having repeated effect, unlike the second.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said in al-Sharh al-Mumti’ (13/133): The phrase “every time” is the only one that implies repetition. So if he says to his wife, “every time you get up you are divorced,” then she gets up, she is divorced, and if she gets up a second time, she is divorced (again), and if she gets up a third time, she is divorced (again). This is unlike the word “if” for example, which does not imply repetition. So if he says to her, “if you get up, you are divorced,” then she gets up, she is divorced. But if she gets up a second time, she is not divorced (a second time).
Based on that, if your husband said “if you contact so-and-so, then you are divorced,” and you got in touch with her and divorce took place, then the matter is finished with, and divorce does not result from your getting in touch with her a second time. This does not need your husband to say that he has retracted these words, because his words “if you contact” do not imply repetition, as explained above.
And Allaah knows best.