This is the kind of stuff that makes my blood boil...grrrrr. You damn right I am angry at the religion that forces mothers to ignore and shun their children. Frankly, there are many who choose to not cutoff limited association with a child. In the end, responsiblity really does fall on the individual, no matter what instruction they've received.
As much as the knee jerk reaction would be to tell her to take a hike, it may not be what you really want. If you can stomach it, and it doesn't tear you up inside, maybe you could try her plan. I say that with the hopes of giving her a view to your new life outside the org, and maybe she will have a change of heart. And if that happens, it gives her the opportunity to "break the law" in favor of love. No gurantee though.
If you cannot take the duplicity of the JW "love", then don't do it. Concentrate on your new family and hope someday your mother can be a part. Either way, good luck and let us know how it turns out.
My .02.