David Yelland is a recovering alcoholic who got help for his addiction when he realised the effect it was having on his eight-year-old son.
Now he's written a children's story, called The Truth About Leo, based on his experiences, to try to encourage families to talk more openly about alcohol problems.
David says his own addiction developed slowly, but he soon realised he had to get better or he wouldn't be able to look after his son properly.
Pupils in London asked David about some of the problems his drinking created.
He said when he'd been drinking he'd often say things he didn't mean. The trouble was, the people he'd say them to didn't know he didn't mean them.
Watch the clip to find out what else David had to say...