Scared to get IUD inserted.

I had a baby 6 weeks ago, and had plans to get this IUD put in tomorrow. However, this last week, my husband and I have had sex a few times. We used a condom every time, but one time he left it in me for a minute after he came, and the condom slid about half way down the shaft since he had softened a bit while pulling out. It didn't come off completely, just kinda rolled down a little so he had to grab it and hold it on while he took it the rest of the way out. I know it's so unlikely, but I'm terrified I could be pregnant again. Is it possible his sperm could have been up by the mid shaft area or is it only caught in the tip? Should I still get the IUD inserted tomorrow or wait a few weeks until I can test and be sure? I have these pills I'm supposed to insert tonight to soften my cervix for tomorrow, but I've been so on the fence about doing it. I'm probably just being paranoid, but can anyone put my mind at ease?