Lack of Relations in Marriage Leading to Sin

Assalaamuallaykum Mufti.

I have been married for a few years and have children. My wife and I have been having a difficult time in our marriage. To the extend that we are not having sexual intercourse.

I am afraid that I might comiit zinah or worst if my sexual needs are not taken care of.

Is self masturbation allowed in this case or if Mufti could please give alternate recommendation.