I am not sorry for them at all. I am sorry that it is causing you pain and suffering, and that if they get caught, they will be in legal trouble, but I do not feel sorry for people who make decisions.
People who make decisions and are responsible for them, rarely want my sympathy, either.
Hopefully they won't follow in my footsteps, but if you knew me better, you would know that worse things could happen to them than to hold a couple of bachelor degrees. And your abstinence policy might not be the ONLY way. They MIGHT be able to take tests high, and still score an 'A.' It sure calmed my jittery nerves down, right before test time.
My path through life has been my burden to bear, and your sons all have their own paths to follow. It is not easy.