I popped a blister Watch
Then I looked on NHS website:
Even though it may be tempting, try not to burst a blister because it could lead to an infection or slow down the healing process.
If you have a large or painful blister, your GP may decide to decompress the blister under sterile conditions.
If a blister does burst, don't peel off the dead skin on top of it. Allow the fluid inside the blister to drain and cover the area with a dry, sterile dressing to protect it from infection until it heals.
If you didn't, sterilise the wound now and put a plaster on.