Confused about the neighbors

My kids are growing up and with each stage comes new joys and new challenges.  Philip is now 6, almost 7, and thrilled that six boys live within walking distance of our house.  I love the small community feel of our little, dead-end street but it seems recently that it's turned into the set of a soap opera instead of a sitcom. 

So I'm trying to share the love of Christ with the boy Philip plays with most often.  His parents are divorcing and I'm happy to provide him with a peaceful haven for a few hours after school.  His mom is at home during this time so I'm not techincally babysitting.  The friend who I will call Charlie is an overall good kid but somewhat on the hyper side but I've grown to love him and he and Philip play really well together.  There's been a few potty humor jokes said and pretend injuries to the groin area but Philip sees that stuff from his church friends as well.  At this age, that kind of stuff seems to be on the minds of all boys no matter how strong his family is spiritually. 

Well, Charlie's mom and I are acquaintances.  I'll listen when she tells me how things are going with her husband and I try to encourage her to turn to Jesus.  Not that I'm trying to be preachy, but He is truly my only source of hope and strength, and I want that for her too.  She is a seemingly nice lady but I don't know her well enough to ask her to babysit my kids.  I don't think I should feel bad for saying that I don't know exactly what is said or done in their house and so I don't want my kids influenced to the point of not being able to come home if they want to (only Philip goes over there, but she's offered to watch all three). 

Here's where it gets complicated. Another mom on the street called me last week. She and I are even more distant acquaintances but she's always seemed very friendly and I know their family to be Christians. She called me with much hesitation as she didn't want to gossip but she told me that she and Charlie's mom are no longer friends due to Charlie's mom saying some very unkind things about her to other neighbors and being involved with things that the mom calling me disagreed with (being places and saying she was elsewhere, lying to her husband about things, etc.). This other mom said that Charlie had gotten too rough with her kids and was not allowed to play there anymore.  The mom was calling me to make me aware of the situation and not trust everything I see or hear.

Now I feel silly writing all of this because it does sound so 6th grade.  But the bottom line is that I love my son and want to protect him with my life.  Where do I draw the line as to whom he can play with, whose houses should I let him go into, how do I say he can play with certain kids if they come to our house but not to their houses?  I don't really think I'm a good judge of character as I'm quite gullible and often buy into whatever the person says. I do know I should pray for discernment and not let my mind go all "after school special" coming up with crazy thoughts of what might happen.

A friend whose kids are older teenagers now told me, "When your kids are little, it's physically exhausting, but when they get older, it's mentally exhausting."  I'm going to be all-around exhausted if I'm in the tough physical and mental stuff all at the same time!