Lots of love to you.
I don't know if you want to, or if you can handle it, but you could call your local sexual abuse hotline. I have done that, and it was just so nice to be able to talk to another human being at length about the suspicions, and what I felt about them -- without being charged $250/hour...
It's all coming down now. You have been so strong, and you will continue to be strong through this. I know the terror, the fear, the urge to vomit, the guilt, the pain, the tears of hearing that suspicion from someone else. You simply cannot fathom that it could be a possibility, despite everything else you've seen.
Just know this: Regardless of whether the suspicions are founded, your children will be OK. Because of you. Because you don't back down. Because you are like a pit bull when it comes to protecting them and getting them the support they need. Every bit of hell you are going through right now is something that puts you one step closer to being able to protect the children in the future. Waiting is hell.
And I am frankly appalled that they don't stop visitations at the suspicion of sexual abuse.
Keep breathing. Stay in touch. We're here.