Gavin Demands $50M & A Mansion From Gwen

Gwen Stefani and Gavin Rossdale's divorce has taken yet another nasty turn, RadarOnline.com has learned. According to an insider, the former couple has begun mediation and the Bush frontman is demanding the marital home as part of the settlement!

Stefani and Rossdale didn't have a prenuptial agreement, but the insider told Rdar, "Gwen can't believe that Gavin is asking for their Beverly Hills mansion as part of the settlement. She thought the only issue of the mediation would be finances since they have already agreed to joint custody of their three children," Kingston, 9, Zuma, 7, and Apollo, 1.

Now, the insider said, "Gavin is seeking at least $50 million from Gwen, along with monthly child and spousal support."

"Based on their extravagant lifestyle, Gwen could be paying Gavin a very large payment every month, upwards of at least $50,000!"

Rather than bulk up his own paychecks touring with his band Bush, the source said, "Gavin is planning on going on a semi-pro tennis tour."

As RadarOnline.com previously reported, Stefani still believes that Rossdale had an inappropriate relationship with one of the family's former nannies, although she has no proof.

So now, "It absolutely disgusts Gwen that he is asking for so much money after she feels he betrayed her."

Even though Stefani hasn't publicly commented on the contentious proceedings, her new single, "Used to Love You," hints at the growing acrimony.

"I don't know why I cry / But I think it's because I remembered for the first time since I hated you / That I used to love you," Stefani passionately sings in the music video.