I understand your sense of remorse, which is shared by many members of your generation. Let me offer some thoughts that might be helpful. First, the ball game is not over. Your teens will be very different in the future than they are now. Adolescents have a way of becoming adults, and thankfully, maturity begins to set in. What appears to be great failure on your part now may turn out to look very different in a few years.
Second, I’ll guess that you were a much better mother than you think you were. Parenting is a very guilty affair, and no one—not one of us—does the job perfectly. We can no more be perfect parents than we can be perfect human beings. The task of raising kids in a fast-paced world is infinitely complex, and life itself takes a toll on our good intentions. But kids are resilient, and they usually manage to turn out rather well.
Remember that the Creator in the Garden of Eden also had “children” who were rebellious. In that instance, Adam and Eve had no television, pornography, bad peers, or other unsavory influences to lead them astray. And yet they were headstrong and went their own way. It is the nature of mankind. What I am saying is that it would be a mistake for you to wallow in guilt for everything your children do wrong.
Kids are exposed to many harmful influences today. It is impossible to shield them from everything negative. We do the best we can to guide them down the River of Culture and try to keep them from drowning. For you to blame yourself for everything disappointing that you see in your children is not biblical, not reasonable, and not fair. On the other hand, it is inappropriate for parents to take the credit for everything good in their children. Each individual is a free moral agent who is able to make independent decisions. Some of those choices turn out to be good and others bad, but you are not to blame for them all.
You did the best job you could when your kids were small. It was done, I’m sure, in love. Now your record is in the books. I don’t doubt that the mistakes you and your husband made were serious and regrettable. But what is done is done. Lay it to rest. Your job now is to pray earnestly for the spiritual welfare of your nearly grown children. Ask the Lord to override your shortcomings and failings, and to work to accomplish His purposes in their hearts and lives. Continue to show love to them, and when your advice is asked for, give it thoughtfully. But do not let the demon of guilt ride heavy on your shoulders. That is a short route to despair.