I have a big dilemma. I am hoping to get some advice here on how to handle it. 

Last week I went to visit "Marie" with my 9 yr old "Matthew" and my baby.  Marie has 2 girls.  "Lisa" who is 3 and a 4 mo old baby.  Marie is married to my husband's childhood friend "Bob".  While we were over at their house, Lisa and Matthew were playing on the gameboy sitting on the couch, playing a board game in front of us.  Lisa even got my son to play barbies with her.  They were also running around and my son was chasing her and tickling her and telling her he was "going to get her".    All in front of us (the moms), the dads were not there.  Towards the end of the visit they were laying on the master bed watching a movie.  Matthew was on one edge of the bed and Lisa was at the other.  Both on top of the covers.  The bedroom door was opened.  Marie would get up about every 5 min to "check" up on them.  She must have "checked" up on them about 5 times in 1/2 hr.  After a few times I found it strange she was doing this so much but did not give it too much thought.

The next morning my husband tells me he got a disturbing call from Bob.  Bob said that while he was tucking Lisa into bed the night before, Lisa told him that Matthew had touched her "there".  She said he "pinched" her there.  Bob did not pursue Lisa telling him more.  She aslo told him that Matthew said he was going to get her.  My husband told him he would talk to me and that we would talk to Matthew.

 We told Matthew about the phone call and what Lisa said.  He was shocked and horrified at what we were telling him.  He said "how can you think that! She is 3! I would never do that!"  We explained that we were not accusing merely telling him about the phone call.  He said the only times he touched her were when he was tickling her.  Here at home we play tickling with the baby and tell him we are going to get him.

That same day I was going to my weekly therapy session with my psychiatrist ( Post Partum Depression).  My husband came with me and mentioned that Bob said in passing that Marie had been sexually abused as a child.   My doctor said it explained her checkin in so much.  He suggested my husband tell Bob that the details are needed from Lisa and how this happened.  This might jof happened during the tickling play and my son might have touched her without the malicious intent.  My husband spoke to Bob and he refused to ask Lisa any questions.  He told my husband he did not want our son anywhere near his daughter.

We feel very bad about all of this.  My husband and Bob have been friends since they were 2.  They are both 39.  We dont know how else to approach this, but we feel they are condemming our son for something very innocent and misinterpreted.  We can't force them on how to approach this with their daughter.  We feel that due to Marie's abuse and not ever getting any counseling she might be reading more into something that is not.