I feel regretful about your child.
I'm regretful about your child. I know how challenging this situation might seem. I urge you, accept my heartfelt regrets.
I feel apologetic for
your child. I understand what challenging the situation might seem. I urge you, accept my heartfelt condolences. I genuinely am saddened for the inconvenience caused. I am hoping that your child will forgive me.