Urgency, which condom size should I use?

That is a very big girth, you need larger size condoms. Like Magnum condoms. A regular size condom would be too tight. But you should have practiced using condoms before now- get some today and practice learning how to put one on properly and how it will feel- and when to remove it.

Purchase several sizes from several brands and try them on. You don't buy shoes without trying them on, right? And poorly fitting shoes won't ruin your life for the next 20 years.