Dear Reno Oppo,
I can see by your statements how upset and violated you feel by the actions of your family member. The hypocritical behaviour of this person has eaten into your relationship with God, both at a personal and corporate level. There are only two possible solutions. Both are direct opposites of each other and difficult to execute.
The first is to cut this offending person out of your life completely. I suggest this with the assumption that you and perhaps others as well, have made several futile attempts to get her to correct her ways. By cutting her off, you reduce the instances she can do you more harm. As it is unlikely that she will leave the church you both attend, you may have to do so. But this strategy is not without risks. Others might notice your turning cold and rally to her side, thus further making you feel like the innocent party being painted as the villain again!
The second strategy is to be gracious. This does not mean that you forget what she has done and that you remain wary of the possibility of future hurts. You also need not put on a fake smile when being with her. Showing grace does not allowing serial abusers to continue to hurt others.
If you think this strategy is too difficult if not impossible, you are right! It is only when the love and grace is felt by us and only when we allow it to flow through us that this becomes possible. You said that you felt robbed of the peace and safety of being in a relationship with God by her. But no one, neither a harsh and abusive family member, spiritual principalities, nor the Devil can get in the way of us experiencing God’s peace and love. Claim the truth in Romans 8:38-39 for yourself and live out of the shadows.