I'm in a relationship with my sister. How do I break up with her w/o hurting her?

I didn't know what subreddit to post this in. I really need some advice. <br><br>My sister and I (F25) had a sexual relationship in the past. We went our separate ways and I ended up getting pregnant with his child. She ended up with a boyfriend and started living with him. But now none of us are together anymore. I had a miscarriage and she broke up with her boyfriend and left him. Now we've reconnected and I feel like we're falling for each other again. I didn't expect this. I don't want to be in a relationship with my sister. This is going to ruin our relationship as siblings. I don't want to be judged by my family and friends. I don't want to be shamed. I feel like we have been doing this for so long and we're older now. We can actually press charges. I told her that we need to stop and she broke down crying and begged me to stay. She's so confused and I didn't expect her to react like this. How do I end this without hurting her as much as possible? Should I get therapy for her? How can I let her know that I'm committed to ending things?