Valerie Trierweiler has given interviews to two French publications describing for the first time what led to her break-up from Francois Hollande last weekend.
Ms Trierweiler told the weekly Paris-Match, where she worked for a long time as a journalist, she did not believe rumours about the affair until a gossip magazine report earlier this month.
She said: "When I found out, it was like I had fallen from a skyscraper."
The former First Lady told the weekly Le Parisien Magazine she and the president had exchanged text messages while she was in India earlier this week because he was worried about her health.
The French leader, 59, has neither confirmed nor denied the report in Closer on 10 January he was having an affair with actress Julie Gayet, 41.
Ms Trierweiler, 48, was admitted to hospital shortly after news of the report and had been living at a presidential retreat in Versailles since her release.
Twice-divorced Ms Trierweiler said she was not "undergoing a period of crisis".
She added: "It's not the first break-up in my life. This one was violent because of the media attention."
Telling Paris-Match she had no regrets, she said she planned to take up her previous life "enriched by a new experience".
Nathalie Kosciusko-Morizet, a leading figure in France's main centre-right party the UMP, has predicted female voters will not quickly forget the dry manner in which the president announced his separation from Ms Trierweiler at the weekend.
The candidate for mayor of Paris said: "I felt like I was reading a sacking letter rather than a break-up one."
Ms Gayet has been keeping a low profile, although friends say she has no intention of becoming the next First Lady.