Heather - I wish I had an answer to this, other than to say that "what's done is done" and your personal integrity matters more to you than it does to your mom, apparently. She is still talking to you, afterall, although perhaps not about things you'd like to talk about.
You asked:"Do I just tell her how I NEVER want to go back again or just lie and play along and hope in 20 years she will speak to me like a normal family member. "
I've been waiting over 25 years for that to happen since my d'f'ing at 15, and no such thing's happened, although my family, esp. my mom, bent the rules a lot, off and on over the years, only to pull away very strongly whenever "counselled" - (or, rather, reprimanded for their waywardness) - to do so. I found, eventually, that it's just too painful to keep putting myself and my child through a kind of "Stockholm Syndrome" situation, where my wishes were not respected.
I've just chosen to stay away from them. For me, that's the best course, although it doesn't have to be that way for everyone.
I myself have often thought about getting re-instated and then fading away, but I feel it isn't worth the trouble. Would it be worth the hassle to do that for you? Only you can decide.
You can also set boundaries with your mom, since she's still talking to you about it; and just tell her the truth; it depends upon what you are able and willing to put up with from her and from the Society. Personally, my tolerance for all the boundarylessness of such a situation is completely gone, and I am A-Okay with setting my boundaries as I have. But it took a lot of years to get where I am, with no support from anyone who really understood the 'lowdown' on JWs. There are a lot of people here who have tried and successfully done other things than my way, and many who, like me prefer to be brutally honest with their JW families and leave it alone.
Whatever you do, do what's best for you and your children. Above all, be happy!