I apologize for how all over the place this is. I’m distraught.

My husband and I had a threesum with a friend of ours a couple of weeks ago and she messaged me this morning saying a man is blackmailing her and telling her he gave her an STD. She slept with him a week before us. She did get tested before she slept with us and was clean, but it could have just not shown up that early. I’m really concerned because I am breastfeeding and I’m scared I could have transmitted something through my breastmilk. My husband is currently at the hospital getting tested and asking for a doctors advice. I’m really upset and don’t know what to do. I feel like a horrible mother for possibly exposing my son to something. She is a close friend and I %100 trust her. I know it’s not her fault. She sent us money to pay for our medication and is extremely apologetic. I’m worried for her because this man sounds insane and he knows where she works and lives. I don’t know what to do and feel like I can’t breathe. Wtf do I do?!?!