Need advice

So, I'm leaving for good to SoCal in a few days and me and my so were planning on having sex before I left, because I want to end the relationship to be honest. So, I'm going to be on the penultimate day of my fertile window (high chances). I was thinking to not have sex but we both really want to. I decided to use condoms, spermicide and he won't cum inside the condom or me. He'll do it out even with the condom and I also thought of getting plan b just in case. Do you think that'll be safe enough and I don't have to take plan b unless the condom breaks? What do you recommend? I'm a little worried because before I used to do it lots of times without condom and I didn't know if I was in my fertile window and nothing happened but now I'm very aware of it I'm feeling a little worried.