Fired from coaching this morning. Need some advice.

This morning I got the call from our travel orgs president that I have been relieved of duties due to an incident that happened during practice last Saturday. It’s a long story, but I used an hour of the two hour practice for my personal BP session and a kid got hurt. I had a men’s league game and was working on some mechanics and wanted to dial it in before my afternoon game. The kids were cool with it cause I was locked in and hitting bombs. They were having a lot of fun and rotating pitchers to try to strike me out. One of the weaker players got up to pitch and I tried to stop it but they begged me to let him. Well, he doesn’t throw very hard and first pitch I drilled one right back up the middle. Ball ricocheted like 75 feet off his leg. I felt terrible but we had a cooler with some ice so we sat him down in the dugout. I finished up my BP and that was that. Had my game that afternoon and went 3-5 with two doubles. I thought nothing of it until I got the call this morning. I tried pleading my case but they are having nothing of it. I guess the kid had some pretty bad bruising on his leg. The league said my conduct was negligent as they are only 9 and I could have really injured someone. I asked if there was any recourse or way back but they were firm on their decision. I’m nervous this will follow me if I try to get another coaching job. Any advice? I apologized and accepted responsibility for my actions. I just want to coach ball.