Made A Big Mistake At Work Last Night

Last night at work, I spilled a drink on one of our regular customers. It was bad timing too, he's known to be the type who gets really angry when things don't go his way. I immediately apologized and tried to clean it up quickly but it was a total mess. My manager came over right away and asked me what happened. I felt my face get hot as I explained. He said there'd be an investigation, which means other staff might find out about this incident too. It's not the first time I've had trouble with precision at work but it always feels like a surprise when something goes wrong. I told my regulars that night what happened and tried to explain myself more clearly. Some were understanding but others just rolled their eyes or acted as if they were better than me. They probably think I'm incompetent now. So here's the thing: did I really do anything too bad? Was spilling a drink such a big deal? My manager seems to be taking it way more seriously than it should be and I feel like this might follow me around for some time. Am I being too hard on myself about this or is there something I could have done better?