وعليكم السلام ورحمة الله وبركته No my dear brother , the Khul is not valid. From the conditions for the Khul to be valid is that the husband should agree to it along with the agreement to be paid atmost the same amount that he paid her as her Mahr. If he refuses to accept the Khul then there is a third solution which is called Faskh ( which means he will be forced to mention the divorce in front of the Muslim judge or the authority for mentioning this word would be transferred to the judge himself ) . And in this case he will not be receiving any payback from her . And I believe you need to consult the official Muslim authority in your place ( the chief of the Muslim community in your place ). And Allah عز وجل knows best .