Pissed and Terrified!!!

My boyfriend of 2 years (now ex) cheated in the past and I had no clue. We've been apart for 3 months but have a child together I recently with to the dr for my yearly checkup and it came back that he had gave me a std, it's curable but still I feel so disgusting I've been so careful and now this. I got checked for everything because lately my ex has not been looking his best. He's lost so much weigh, no appetite, and little to no energy this worries me so much because he will have sex with anyone sometimes oral and come kissing on our daughter. My blood is boiling how can one man be so disgusting he's not with the girl he contracted the std from and she has given him one in the past as well (before my time) but I thought he had changed I guess not. How can I pick a man that's abusive, alcoholic, and now disgusting to be my daughters father I feel like I have failed her I'm literally in tears right now!