Get off the cross SuperMiller, we need the wood.
Seriously. First, when I think of a random question, I don't think of questionable child molestation. I think "I wonder if my dog actually watches TV while I'm gone. He seems to understand how the remote works", or "My coworker frequently eats in the bathroom, anything I can do to make this less awkward, or should I just show up and go potluck with her one day?"
If you're going to talk about a serious subject, because as you so eloquently point out we clearly only talk about fluff here, maybe post a teaser in the subject line. Something slightly less innocuous than "Random question, WWYD?".
Out of all the boards on the bump, Snarky & T-TTC seemed like the best audience for this? Not, say, Parenting? Parenting after 35? School-Aged Children? Single Parents? Blended Families? Special Needs? Christ, I think Crafty Moms might have been a good choice for you.
As for your question, I'm not sure if you're asking if your SILs trauma was legitimate or created, or if your Hs reluctance to put your son in daycare is valid. Regardless, counseling is the best answer for you. Talking with a professional with a background in child abuse, molestation, or repressed memories is probably the best place to start. For one, it sounds like you don't believe your SIL and that is some heavy stuff. It also sounds like you and your H are at odds on how to talk about difficult subjects. Best to discuss this with a professional, not just a bunch of internet strangers who only care about booze and road trips.