Michelle Williams 'Questioned Life' During Depressive Episode 3 Months After Surprise Proposal

After a devastating struggle with the mental illness, the singer is once again happily looking forward to her wedding day with Chad Johnson

After getting engaged to her dream man in March, Michelle Williams thought she had it all.

But as the former Destiny’s Child singer began planning her summer wedding, the star fell into a deep depression that impacted all aspects of her life — including her new engagement.

Unbeknownst to fans, the singer secretly broke off her engagement just weeks after Chad Johnson, a pastor she met a year prior at a spiritual retreat, popped the question.

Though they quietly worked on their relationship for the next three months, Williams again broke up with Johnson at the end of July hours before she drove herself to an L.A. area hospital. Days later, she checked into a treatment facility.

“I thought I was over depression. I thought, ‘I’m good!’ I’ve got love, I’m working out,” the entertainer, 38, tells PEOPLE exclusively in its latest issue. “But I was so angry. The rage built up in me. I did not attempt suicide, but I was questioning [life].”

Williams first battled depression as a teen, and the mental illness was exacerbated during the height of her fame with Destiny’s Child. When the familiar feelings of hopelessness began settling back in this past spring, the star brushed her demons under the rug to focus on her upcoming performance at Coachella alongside Beyoncé and Kelly Rowland.

“The entire year we were rehearsing every day for hours,” she says of their grueling schedule. “I was burying it, and before you knew it, I was looking up out of the pit like, ‘Oh my God.'”

Amanda Friedman

For more on how Michelle Williams battled through depression to find lasting love with her fiancé Chad Johnson, pick up the latest issue of PEOPLE, on newsstands Friday.

But after their highly anticipated performance in April at the annual music festival, Williams hit her breaking point. “I’d been there before in that darkness,” she says. “I was like ‘No, you better go [to the hospital].’ By the time I got there, I was stable.”

Though she pushed Johnson to leave, he refused and tried to be as supportive as possible as she sought further treatment at a nearby facility. “I would’ve understood [if he left],” says Williams. “He’s been praying for a wife. He didn’t pray for a depressed wife.”

Anais and Dax

Previously the team chaplain for the Pittsburgh Steelers, Johnson finally had clarity about why their relationship had been suffering and just wanted his future wife to get healthy.

“Some of the things said and done were very hurtful,” says Johnson, 41. “But I was like, ‘I don’t even want to talk about what happened. Get well and we can work on us later.'”

Anais and Dax

Continuing to undergo individual and premarital counseling (which will be documented in their upcoming OWN reality show Chad Loves Michelle (premiering Nov. 3 at 9 p.m. EST), the couple — who are waiting until their wedding day to consummate their marriage — are now back on track and looking forward to their future together

“People fall off the fitness wagon, people fall of the wellness wagon, but I can’t fall off the [therapy] wagon,” says Williams. “I have to get healed to live this happy life.”

Adds the star: “It’s not just about marrying Chad. I finally found someone to do life with.”