The Scottish soap actor's character Robbie Fraser will soon suffer domestic violence from partner Will Cooper (Scott Ryan Vickers).
Robbie's policeman boyfriend Will pins him up against the wall moments after he proposes to him.
Lamont told the Daily Record: "I hope a storyline like this opens up a dialogue for people if they need it. It could become a catalyst for conversation. People tell me they watch River City with their mums, a lot of guys especially."
Referring to his own homosexuality, the star recalled: "When I first told my mum it was mortifying, there were a lot of tears. Mum's biggest thing was worrying what people would say about me, without really knowing me.
"But it's all fine now. It's just one part of my life, one aspect of my character. It's not what defines me."
Lamont, who has been with the BBC serial since 2009, has never previously spoken about his sexuality.
"I've never really felt the need to mention it before, but I'm in a relationship with a man and I'm very happy," he explained. "I don't talk about my partner publicly, because this is work and he's not part of that."
River City continues next Tuesday at 8pm on BBC One Scotland.