You said it all in your opening post...you know you don't fit in with the witnesses and it will cause nothing but grief for you to go back, only to get df'd again.
It may be best for all if you just tell your mom the truth Just like you are telling us.
Welcome to JWN, by the way. This site can be a huge help to you in the days, weeks, months and years ahead. You will need support and the people here are wonderfully loving.