Prince William's ex-girlfriend Kate Middleton has vowed not to betray the British royal by selling secrets from their four-year relationship following their highly publicized break-up over the weekend.

The couple, who met as students at St. Andrews University in Scotland, announced their split on Saturday and Middleton has been tipped to earn millions if she spills secrets on the prince and his family.

But the 25-year-old told is reported to have made a pact with Prince William never to discuss their relationship publicly.

A friend says, "Kate is not that kind of girl - she has too much self-respect to dish the dirt on anyone. She is a decent person."

The pal reveals Middleton was taking the break-up well and denied speculation Middleton was dumped by the prince.

She says, "She was cool and quite relaxed when she told everyone. They were all a little surprised by how unemotional she was. She almost seemed relieved it was over and it was out. Everyone is focusing on how William felt trapped and dumped her. The truth is it was not like that at all. It was by mutual consent."