Chad Kroeger cheated on and left ex for new fiancee Avril

Although fans are sending nothing but congratulations in the direction of newly engaged couple Chad Kroeger and Avril Lavigne, there is one person who isn’t so happy for the pending nuptials: Chad’s ex-girlfriend whom he cheated on to be with Avril.

According to Radar Online, 27-year-old Kristen DeWitt was quietly dating the rocker for years before he cheated on her and left her for the Canadian singer.

The source tells Radar Online, “Chad and Kristen were happily dating until they made a mutual split in May.…His engagement to Avril completely caught Kristen off guard and the timelines don't match up. Chad had to have been seeing Avril behind Kristen's back."

In addition, DeWitt reportedly took to Twitter and wrote, "The moment u find out ur ex of four months engaged the girl he was cheating on you with! #classic.”

Kroeger and Lavigne announced their engagement days ago after six months of dating. The Nickelback singer reportedly makes the 27-year-old “very happy.”