The Oscar-winning Milk writer wrote an open letter last month after his former college rescinded a speech invitation over images released in 2009 of him having sex with an ex-boyfriend, saying that he "refused to be shamed".
"If you invade my privacy, this is what you will find," he wrote. "I have sex. It brings me joy, fosters intimacy and helps love grow...I am the victim of this 'scandal', not the perpetrator."
Speaking to Digital Spy after stepping out with Daley at the Battersea Power Station first annual party, Black said: "People have been so incredibly supportive.
"It was about time [I addressed the picture leak]. I always just sort of think it'll disappear, but it came up again.
"Cleve Jones, who's in Milk, is like a mentor to me, and he said, 'Girl, you need just to say it and let people know what's up', so I went ahead and did that. It was good to finally get it done."
Describing Daley as "the best", Black said of the Olympic diver's acting ambitions: "I think Tom can do whatever he sets his mind to."
On how he copes with a long distance relationship, the 39-year-old American explained: "I still split my time between here and Los Angeles. I really only have to show my face in LA so they don't think that I've died."
Daley, who beckoned Black into photos with affectionate calls of 'Lance', took time at the event to gush once again about their relationship, which he revealed in a YouTube video last December.
"It's been pretty crazy since the whole shebang happened, but it's been fun and everyone's been really supportive, so it's all been good," he said.
The pair were at the party to watch special performances by Sir Elton John and Tom Odell. The Hobbit's Luke Evans, Game of Thrones star Kit Harrington, Grace Jones and Will Young were among the other celebrity guests.