Is my marriage to my paternal cousin permissible, knowing that my mother saw my wife's aunt breastfeed me once, and I married her after her mother affirmed the permissibility of the marriage because the suckling was less than five satisfying sucklings? And if the suckling is proven, what should I do about my son?

The prohibitive suckling is not established except by evidence, such as the acknowledgment of the spouses, or by clear proof (two men, or one man and two women, or four women, or one woman). Here, there is neither an acknowledgment nor clear proof. Based on what was previously favored in Fatwa no. 34732, you are not obligated to separate from your wife due to the incomplete number of five sucklings.