I haven't read all of the above comments but a couple of people mentioned being the best husband you can be. This is really good advice. The WTS has the R&F convinced that once someone leaves "the truth" they instantly become immoral, therefore, your wife probably fears that this will happen to you. Let her know that nothing is going to change just because you disassociated yourself and she wants to remain a witness.
Just reassure your wife of how much you do love her and start doing more activities with her. If you can get her to meet other people that aren't witnesses and show her that they are not evil that may help also. People fear the unknown.