Arrested but not charged

Hi everyone. I am freaking out a bit. Here is the situation... My husband and I are at the end of the paperwork portion of the home study. We went and did our fingerprints and my husband's arrest from 2010 came back. This is extremely frustrating because this was supposed to be expunged (but that is a whole other issue). Anyways, now we are getting all of the police records and whatnot for our agency to review. The police records sound terrible and I am very concerned they are going to say they don't want to work with us anymore. They asked us about arrests during our intake interview and we both honestly forgot about this because it was so long ago and charges were dropped the next day. He was 21 years old when arrested. He was living at home with his parents when an argument escalated. He had been struggling for a little while with depression/anxiety at that point and did not have it completely under control yet. He is actually adopted and found out a little before this fight who is birth mom was and the fight had something to do with that. I must also say his parents were very difficult at this point in time, but that doesn't excuse his behavior. Things got heated and he went to the kitchen and grabbed a knife and threatened his parents with it. They told him to drop it and he set it down and left the house. They called the police and he cooperated fully with them. The arresting charge was aggravated assault with a weapon and that is a felony. The next day, the district attorney spoke to him and dropped the charges and he completed a couple of therapy sessions per their suggestion (he was already in therapy). I know this is very alarming and I am terrified. The person he was when he was 21 is not the person he is today. He is a special education teacher now and would never hurt anyone. He is working on writing a personal statement about the arrest. Does anyone have suggestions about what to include or what to say? Anyone ever moved forward after something like this coming up? Thanks!