Lissett, Good for you. It is a symptom of the dysfunction that his mom isn't seeing it for what it is - a squalid betrayal of you and your family bu the man that she raised. This not wanting to take sides is just stupid and cowardly. She can say she doesn't approve of his conduct, and endorse that she disapproves of the children being introduced to the OW, and will not facilitate this.
None of this would show that she doesn't love her son, just that she has standards. As it is she is spineless and morally indefensible. You cannot waste your time with people like that. Save your time and energy for the many people who love you. She will be the loser in the long run.
My MIL has been totally supportive, and calls me regularly. SHe still loves my h, and prays for him, but believes that what he has done is wrong, and told him so. My kids have a very good r with her, and respect her tremendously. Her gain.
LOL Angelica
I have just eaten a Brownie, and plan to have another with some hot tea. Very English