Bobby Brown speaks exclusively to Robin Roberts in new 20/20 special

For the first time since his daughter's death, Bobby Brown is talking publicly about the devastating loss.

The former singer sat down with Robin Roberts for an ABC exclusive focusing on his new book coming out this summer.

Along with talking about Bobbi Kristina, Brown reveals new details about his often rocky relationship with his late ex-wife Whitney Houston - including the first time he saw her do drugs.

"When I showed him a picture of her from his wedding day and asked him what thoughts come to mind and he said how happy and loved but he also said that was the first time he saw her doing hard drugs - the first time he walked in and as he said it, was doing a line of cocaine," said Roberts.

You can watch Robin Roberts' exclusive interview on 20/20 - Bobby Brown: Every Little Step I Take Tuesday night at 10 p.m. on 6abc.