Use the diaper.

You feel like getting up to use the toilet would raise too many questions so you just release your bladder into the padding. You feel the warm liquid pool under your bottom and then the wetness spreads to your thighs.

"Oh no." You gasp.

"Huh?" Stephen turns from the TV.

Standing up confirms your fear. Your diaper has leaked. There's two small wet patches on the cushion where pee leaked out the leg holes.

"Sorry." you say, turning red. "I'm going to have a shower."

"Don't worry about it." He says as you head to the bathroom. Somehow, him being supportive seems more embarrassing than if he was making fun of you.

In the bathroom, you examine the diaper and your pyjama pants. You can see where the leak came from. It looks like you didn't have the leg holes tight enough and the leak guards weren't standing up. You make a mental note to do a better job next time.

After your shower, you return to your room and find the open package of diapers still on your bed. You don't really feel like putting another one on right now but Stephen will be suspicious if he notices that you're not diapered when you return.