Sorry but I don't understand WHY you need to call Bethel about this ????
Why don't you just call your Mother In Law (or better yet have your husband call her ) and tell her, her other son told you she didn't feel welcome in your home . Then explain she is free to come to your home to see the grand children and that in the future if she wishes to give them gifts or money it is more appropriate for her to do it in person .
Be an adult about this give her the benefit of the doubt . Maybe she does feel since you left that she is not welcome . Would it really hurt anything to just call and clear upo the mis-understanding ?
I get it . Your family went through some horrible crap ,and your child should never have been treated and abused as she was . However now the man is put away and you have a fresh start . Be a good example , don't let the foolishness of the MIL bring you down to her level .Rise above it be the better person and extend the 'olive' branch .
My humble opinion .....I don't live in your shoes ......but sometimes we need to see through someone else's eyes .