Brandi Glanville finds co-parenting ''frustrating''.

The 'Real Housewives of Beverly Hills' star has sons Mason, nine, and Jake, five, with former husband Eddie Cibrian - who cheated on her with and is now married to Leann Rimes - and Brandi says sharing the kids with them is tough.

She told E! News: ''It's just frustrating. But co-parenting is something we have to do.''

Brandi, 40, recently blasted Eddie on Twitter for preventing her from speaking to their sons while they were staying with him and LeAnn.

She wrote: ''Ive been trying to get a hold of my kids 4 over an hour no response to my calls, emails or messages. Maybe twitter will work (sic).''

The tweet provoked a defensive response from LeAnn, who soon wrote: ''Funny, she just got off the phone w/ them. Sorry, we were doing baths, homework & dinner. All good!

''The phone rang, I picked it up. Never saw this til after. All you gotta do is call (sic).''

Brandi previously revealed she believes her acrimonious relationship with LeAnn will drastically improve once the singer gets pregnant because it will help her to learn boundaries as a mother and stepmother.

The 'Drinking and Tweeting and Other Brandi Blunders' author said: ''Hopefully, they'll have a child of their own and she'll understand better what a proper boundary is for a stepmother and a mother.''