Ashton's Alleged Mistress I Didn't Torpedo His Marriage!

Sara Leal -- the 22-year-old lady who is said to have slept with Ashton Kutcher the beginning of this summer -- claims that she is not the cause of the collapse of the marriage of Ashton and Demi Moore ... According to TMZ, she was what you may call "bump in the road."

Sara says that, Ashton and Demi had issues way before she hooked up with Ashton Kutcher -- but was she the straw that broke the camel's back?