One more thought! If your husband wants to go to meetings! ask him if you could change to a different Kingdom Hall! Just one more small step!
The big moral problem you are having is that your Husband is lying to his mother!
Express to your husband that you do not like the lying! and would like to know why he feels the need to lie to his mother? Is there another way to solve the issue with out lying.
Tell your husband the next time he speaks with his mother that he should state," When you see me at the meetings, you will see me.
Perhaps you can state to your mother in law, "Please do not ask me about my attendence anymore because might force me to come up an excuse which is worse than lying, and you know what happens to liars. It is better to be in good standings with Jehovah than with you."
I hope that helps!