Dis, is there any way you can get a photo of these notes without you Dad seeing you? Perhaps you could show them to your husband, telling him how wrong you know it was of you to go through your Dad's bag, but it is important for him to see this in order for him to protect his children. Ask him not to say anything to your father right now. You need time to digest this.
While I would suggest not taking sides in order to keep your husbands mind open, I would ask your husband not to allow your children to go out with this man in service,or to be alone with him, even if he is with them, just to be safe. It doesn't matter if the molester was never brought to justice right now, the issue is protecting your children. Remind your husband that molesters don't do this in front of others, so there will not be any witnesses.
My heart goes out to you, dis. You are in a lousy position, but the children are the important thing here.