Stephanie Santoro says she and Jon Gosselin exchanged hundreds of steamy text messages. Now the former Gosselin nanny is sharing them exclusively with INSIDE EDITION.

Santoro tells INSIDE EDITION why she kept all of the text messages. "Once things started getting serious and getting to what it was, I figured I'd better keep them just in case."

Just two days after she says they first became intimate, there was this exchange:

Santoro: "U make me so happy. I never would have thought this would have happened. But I am so glad it did. =)"
Gosselin: "Agreed - But I want to be super careful with our feelings and around our kids. I don't want anyone to get hurt just in case things don't work out."

Santoro expressed her romantic feelings for Gosselin at length, she calls him "huni," and he calls her "love." Here's another typical exchange:

Santoro: "It all feels so good and so natural n real when we are together. I would love for it to stay this way and get better n better."
Gosselin: "I feel the same way. I'll talk to you later love."
Santoro: "xoxo thank you for being so amazing to me."
Gosselin: "ditto."

"All of women are going to ask, what did you see in Jon Gosselin?" asks INSIDE EDITION's Paul Boyd.

"Everyone asks that...Jon's a very sincere, very honest – or what I thought was a very honest person, and he was very fun-loving, always wanted to be family-oriented, and I saw good in him."

She says the six-week affair ended when she says she found out that Gosselin was cheating on her with two other women, magazine reporter Kate Major, and current girlfriend Hailey Glassman. She gave him an ultimatum...it was Hailey or her.

Santoro: "Do you think U could give up Hailey..."
Gosselin: "I dont' know whats going to happen."
Santoro: "What would U like to see happen?"
Gosselin: "Chill and have a good time... right now the public is scrutinizing everything I do."

"You ultimately came to realize Jon was trying to have it both ways...you in Pennsylvania, Hailey in New York"

"I'm not going to be played and I don't want to be the other girl," she tells Paul Boyd.

"What do you want to say to Jon?"

"It's time to be a man, to realize what you did was wrong, and tell the truth, the real truth," she says.

Gosselin denies ever having a sexual relationship with Santoro.