I agree the hardest thing in the world is seeing your child struggle emotionally, financially, or physically. But just as we had to make our own mistakes and deal with the consequences so do our children.

I used to "warn" my adult children ... if you do X, Y will happen. They would do what they wanted anyway and just resent my interference all the more. Once I started keeping my opinion to myself I noticed that they actually ask my advice now and take it more often than not.