Breast feeding and one night stand with acquaintance

Hello, please before any one judges me, I am a single mom of a 10m old. I went out had one beer and then slept with someone. We used protection. I did make out with him. He’s an acquaintance at the very least. I am worrying that I could get my baby sick. I am only human and I need to forgive myself. My mind is telling me I missed everything up for myself and my baby. I’m disappointed in my decision but I have been horny since becoming pregnant and I couldn’t hold out until I was done breast feeding. Ugh. I’m going to get tested in a couple weeks. Am I a bad person?