United Kingdom, July 20 -- Heidi Montag has struggled to balance her parental responsibilities with launching her pop comeback.

The 39-year-old star recently co-headlined Neon Skies Festival alongside Kesha and Slayyyter - but Heidi acknowledged that it's tough to balance her various commitments.

Heidi - who has Gunner, eight, and Ryker, three, with her husband Spencer Pratt - told Us Weekly: "You know, my children [Gunner and Ryker] are my priority, so I wanted to give space for them getting sick or me getting sick or who knows anything happening.

"So little by little, I've just been working on this show since I got the call, and then really ramping it up in the past few weeks as well. I've consistently been doing rehearsal for months...