It would be terrifying for any parent to find out that their child, whom they raised with utmost love and care, is being mistreated by their partner in a relationship. You may feel powerless, helpless and may not feel like you have say in the matter, but it is not true. You have all the right to provide support, to help your child and to let them know how it's alright to get out of an abusive relationship.
Having said that, you must understand all forms of abuse. Most people accept abuse only in its physical form. However, emotional, verbal and sexual abuse are also other types of abuse you must be aware of.