My Heart Hurts

Well, today is a day that I knew would come. I know with 4 kids there will be many more of these days. I let Tyler go across the street with a group of boys to play at another 2nd graders house. This is a first for me. I would much rather be able to see my children play and observe what they are doing. But I stepped outside of my comfort zone and let him play in this other kids yard. I walked over to get him for dinner and found him playing alone in the sandbox. I saw the rest of the boys playing baseball. I immedaitely assumed that Tyler was playing alone by choice. I somewhat scolded him saying,"Tyler if you go over there to play with the boys then you shouldn't be playing alone in the sandbox." He didn't say anything until we were out of the other kids sight. Then he lost it and began crying telling me that they said he couldn't play because he needed to practice. Then they told him that he couldn't play because they wanted the teams to be even.(LUMP IN THROAT AND HEART HURTING) These kids were mean to my son!!! I apologized and told him that I am sorry that happened to him. I explained to him that if that happened again that he could come home, I don't want him to stay if they are being mean to him. I don't even know what to do!! I want him to play with other kids but I am not sure I want him to go over to that house again. I don't want to be that overbearing Mom but I want to protect my son. This stinks!