Mostly, I believe that I needed some time to just get healthy myself and gain a better perspective on dealing with them. So, I don't know if anyone knows an appropriate way to get back in contact with BP family members after establishing NC.
I don't think there's anything wrong with asking for space in a relationship. From what you wrote, it sounds like you have been using this time to work on healing and skill-building, and that seems like a positive thing to me. I could be wrong, but it doesn't sound like your decision for no contact was meant to be vindictive or punitive in any way.
I can understand the conflict you are feeling. My faith is extremely important to me, too, and I have not had any direct contact with my mother in about three years now. There are a lot of ideas about love and forgiveness in Christianity that can be difficult to reconcile with estrangement. Do you mind my asking which faith you adhere to? It may help you to talk with someone whose advice you trust such as a pastor or friend. My pastor has been understanding and given me good advice on how to pray. At this point, I feel I have forgiven my parents and accepted that they are who they are. I have done the work so that I feel pretty neutral about my mother rather than terrified or angry, and if I ran into her at a family event or something I would be ok with it. Still, I do not want to be close with her and am not interested in pursuing deeper contact with her, and I don't feel badly about that. It is likely I will need to be in more regular contact at some point as my parents are getting older and are not in very good physical health, either.
In my case, I decided to try limited communications with my father about a year ago. I did have some anxiety about how to resume contact with him, but ultimately decided to pick a morning when I felt centered and try giving him a call. He was very happy to hear from me, expecting everything to go back to the way it was before NC. Right now there is some tension because seeing me (well, I have the feeling it's more about seeing my children) in person is a high priority for him, while I am not enthusiastic about that. I am happy just talking on the phone and exchanging very neutral cards with my parents for holidays, etc. I have stated my boundaries and will continue to do so because I feel good about having some limited connection to him, still I recognize the reality that he is not able to understand them and wants things to be different.
The others have some good questions for you. I would also ask, what kind of communication with your sisters would feel good to you? How often would you like to be in touch, and in what way (e.g., e-mail, phone, cards, etc.)? Also, my therapist was very helpful in helping me decide how to resume contact and when. Do you have a therapist of your own you can talk to?
Wishing you peace,
PF