Obviously, this matter should have been addressed in the Separation Agreement when you got divorced. In order to know for certain whether it was in fact addressed in a general way one would have to review the terms of the Separation Agreement carefully. There may be a provision regarding marital funds or property, of which this deposit is one. This is not money that was acquired after the separation and divorce but in fact was money that existed during the marriage.
If you are living in the New York City metropolitan area, please contact me to arrange for a meeting to review the Separation Agreement and discuss the matter at greater length.
Leonard M. Weiner, Esq./Divorce Solutions