Husband taking an oath that his wife will be divorced if he camps with his friends

Q: I was out camping with some friends and we had a dispute. So I told them that if I ever camped with them again, my wife would be divorced and I took an oath on that. Later, I went out to the same place with them despite taking the oath of Talaq (divorce pronounced by a husband). The divorce became effective in 6/5/1391 A.H. Then I took my ex-wife back towards the middle of Rajab, 1391 A.H. And there were witnesses to that. I had never divorced her before or after that time, and it was not in return for a consideration. My wife is still in her `Iddah (woman's prescribed waiting period after divorce or widowhood). Is she lawful for me?

(Part No. 20; Page No. 230) A: You made the Talaq and oath contingent on your returning to this place with your friends and you returned. You also made one pronouncement of divorce and took her back during her `Iddah in the presence of two witnesses. Because you had never divorced her before or after that time, your revocation of divorce is valid, and there is no need for a new marriage contract or her consent. However, you must expiate for breaking your oath, which can be done by feeding or clothing ten needy people or freeing of a slave. If you are unable to do any of these things, you must fast for three days. May Allah grant us success. May peace and blessings be upon our Prophet, his family, and Companions.