Ashton Kutcher's alleged mistress -- the FIRST alleged mistress -- claims she feels "vindicated" by Demi Moore's divorce statement ... telling TMZ she hopes people will finally believe her story about sleeping with Ashton.

TMZ spoke with Brittney Jones -- who claimed she got busy with Kutcher in 2010 after meeting the guy at a bowling alley. Jones' credibility was called into question when she capitalized on her sudden fame by releasing a sex tape .... which did NOT feature Ashton.

Ashton's lawyer released a statement at the time Brittney was in the headlines, insinuating her story was a lie ... but not entirely denying

Now, Jones tells TMZ ... "Although divorce is often sad I do feel somewhat vindicated."

She adds, "For so long people have thought that I was dishonest or just making up my passionate nights with Ashton, when in fact I was being used."

"Ashton told me that both he and Demi had an 'open relationship' and that he was not in fact cheating. Now I can tell all the facts about how Ashton really was, and hopefully people will believe my side of the story."

Still, Jones says, "I feel for Demi very much and wish her nothing but the best during this hard time."

Read the whole story: TMZ