The professional dancer announced in February that she was leaving the BBC One series after seven years.
In a new interview, Oti said she "cried for hours" over the decision but felt it was the "right time" to leave.
She told the You magazine: "I lived my best life on that show and it gave me the career I have now, but you need to know when it’s the right time to get off that wave and try new things.
"I didn’t want to hold on and get to the point where I wasn’t happy any more. I left when I was at the peak, in terms of working on the show."
Oti added: "It feels like I’m leaving family behind – even the backstage team, the people viewers don’t get to see – but when you know it’s time to go, you know."
Oti's exit follows her joining ITV's Dancing On Ice as a new judge.
The dancer is part of this year's panel together with Ashley Banjo, Christopher Dean and Jayne Torvill.
Although her first series isn't over, it's been reported that bosses are already keen to get Oti back next year.
"She is full of good vibes and just makes everyone laugh. she is so infectious. She's here to stay hopefully!" a source said.
Meanwhile Oti is also set to host new dating series Romeo & Duet.
Starting in April, the new dating series will see singletons matched up with people they can hear sing but not see.
For now, Dancing On Ice continues Sunday nights on ITV.
Oti said: "It’s about love with a little bit of a twist and showcase of talent, it’s fresh and fun, and I hope everyone’s going to love it as much as I do."
You can watch Dancing On Ice online via the ITV website.