I hate mean 4th graders

Skywalker started 4th grade this year. Due to his Asperger's he's always been a bit of a recluse... and had a bizarre sense of humor. He's weird, OK he's weird but he's still a great kid. I see it, other adults see it, but kids... kids aren't so kind. I asked Skywalker if he had 4 or 5 friends he would like to invite over for a sleepover for his birthday party in October. I told him that we could go go-cart racing and mini-golfing. He named off 3 boys and then said "that's it, I don't have any other friends." This broke my heart. Yesterday I was asking bff K's son who is in the same class as my son
Me: "So does SKywalker have friends?"
K's son: "uhhh yeah, some"
Me: "Do they make fun of him?"
K's son: "No, some kids call him gross. Some kids want to be his friend but are scared the other kids will make fun of them"

This breaks my heart. Absolutley rips my heart out stomps on the ground. I do NOT want this for my baby. What do I do? What can I do?