Firstly well done for running 10k!!!
As for the blister I would be tempted to leave it. In my experience that's the best thing to do cos anything else will make it hurt more! Mind you, in the past I have burst them with a sterilised needle to get the fluid out & save it from bursting on it's own & possibly causing more of a hole. I'm not recommending that though cos it's prob not the right thing to do!! lol.....
Just googled it for you & indeed, I did the wrong thing Most blisters heal naturally and do not require medical attention. As new skin grows beneath the blister, your body will slowly reabsorb the fluid in the blister and the skin on top will dry and peel off.
The unbroken skin over a blister provides a natural barrier to infection. The skin should remain intact to avoid infection. Never pierce a blister with a needle. Allow it to break on its own once the skin underneath has healed.
Cover small blisters with a plaster (adhesive dressing). Larger blisters should be covered with a gauze pad or dressing that you can tape in place. If you have a blister that is painful or in a position that makes it likely to burst (such as on the sole of your foot), cover it with a soft dressing to cushion and protect it. Change the dressing daily.
If a blister bursts, do not peel off the dead skin on top of the blister. Allow the fluid inside to drain, then cover the blister and the area around it with a dry, sterile dressing to protect it from infection until it heals.