The Miranda Lambert-Evan Felker situation is getting increasingly complicated. Now, Felker is under fire for his shoddy treatment of ex-wife Staci Nelson.

She Didn't See It Coming

Just last week, Lambert's ex-husband Blake Shelton sent out a cryptic Tweet about karma following the news she had hooked up with married musician Felker. Allegedly, Felker filed for divorce from Nelson just a couple of weeks after starting things up with Lambert.

The details on how their separation came to pass have just been released as a source close to the couple revealed all to PEOPLE. According to the insider, Felker totally blindsided his ex by suddenly filing for divorce midway through February.

"The notion that [Felker and Nelson's] divorce happened for any reason other than that is complete bulls**t," the source revealed, referring to Felker and Lambert's blossoming relationship.

A Digital Romance

The insider explained how Lambert and Felker, both 34, originally connected via a text message. His band, Turnpike Troubadours, opened for her during a tour and the two reportedly got close over the three dates in early February.

"They had never met and she had started texting him about looking forward to playing together and getting to know each other ... It started very much about work. He was completely thrilled. By the time he was leaving for tour, it had become a lot flirtier," the insider revealed.

Felker and 33-year-old Nelson were married for just under two years. They were like best friends, according to the source, and she was well aware of the flirty nature of Lambert's messages before the two headed out on tour together. 

"He knew it was flirty and crossed a line with Staci. He showed her the whole thing and felt bad about it,'" the source added.

Felker reportedly explained away the messages by claiming the kind of money he could make with Lambert would solidify the future of their kids and grandkids.

It Happened Fast

The source is quick to add, however, that Lambert and Felker were only out on tour together for three days, with the Turnpike Troubadours musician still acting as though he was married on the first two days. On the third day, however, he didn't even bother to ring home.

Felker then purposely missed his flight back to Oklahoma when the tour was over. He continued on the road with Lambert and sent an e-mail to his wife to tell her he wouldn't be home.

As the days dragged on, Felker ghosted his wife as Lambert shared cryptic posts on Instagram.

"I do this thing called whatever I want," was written on a mirror in red as she posed in one shot.

In another, she posted a photo of his favorite beer and his graphing paper, which Felker allegedly uses to write lyrics.

Karma Will Take Care Of It

According to the source, if it wasn't for Lambert, Felker would still be with Nelson. There was nothing to suggest anything was wrong with their marriage.

He reportedly came clean to her in March, admitting everything and taking responsibility for his actions. The source maintains Felker should have been stronger, however.

Lambert, on her part, thinks Felker is the one. A source claimed she is ready to settle down with the country musician because of their undeniable chemistry.

As rumors swirled about Felker and Lambert, Nelson took to her own Instagram page, posting a Story Thursday about how difficult her week had been and urging followers to stay strong.

Meanwhile, Lambert's ex, Shelton, maintains that he wasn't alluding to her when he tweeted about karma recently.