Accidentally Filled My Girlfriend's Sister Raw... Now She's Shaking Uncontrollably!

It was supposed to be a quick, innocent visit while my girlfriend was at shower. But her sister looked too tempting in that dress. One playful wrestle turned into heavy making out, then my cock accidentally sliding raw into her tight, dripping pussy. I couldn't stop. I fucked her harder and deeper until she came so intensely she started shaking uncontrollably, legs trembling, eyes rolling back.