Kristen Wiig is opening up about the “most difficult time” of her life.

Speaking with InStyle for their September cover story, the “Wonder Woman 1984” star recalled her and her fiancé Avi Rothman’s emotional and stressful journey with in vitro fertilization (IVF) and how they ultimately decided to have a child through a surrogate. Wiig, 46, and Rothman, 47, welcomed their now 9-month-old twins back in June.

“We’ve been together for about five years, and three of them were spent in an [in vitro fertilization] haze,” Wiig began. “Emotionally, spiritually and medically, it was probably the most difficult time in my life. I wasn’t myself.”

“There are so many emotions that go with it — you’re always waiting by the phone and getting test results, and it was just bad news after bad news,” she continued. “Occasionally there would be a good month, but then it was just more bad news. There was a lot of stress and heartache.”

“It was a long f—ing time,” Wiig added. “It got to the point where I just kind of stopped talking about it entirely, because I would get sad whenever someone asked. It was just part of my life. I gave myself [hormone] shots in airplane bathrooms and at restaurants — and those shots are no joke.”

The actress said it was difficult “not to personalize” when she received negative results, but noted that she found comfort meeting other women who had also gone through a similar experience.

“You go through so much self-deprecation, and you feel like your partner may be seeing you in a different way and all this other stuff we make up in our heads,” Wiig explained. “But when I did talk about it, every time I said that I was going through IVF, I would meet someone who was either going through it, about to go through it, or had a friend who just did it. It’s like this underground community that’s talked about but not talked about.”

Though she was initially against other options  — and was determined to carry a child herself — the “Saturday Night Live” star said she eventually realized she “needed help.”

“I remember when our doctor mentioned going other routes, and I was just like, ‘Nope. Don’t ever bring that up again. I’m getting pregnant. I’m doing this,'” Wiig recalled. “I finally realized that I just needed help. And, thank God, we found the most amazing surrogate.”

The “Bridesmaids” actress went on to describe the ups and downs of having another woman carrying her child.

“So many things were bittersweet,” Wiig said. “I was over the moon feeling them kick for the first time, but then I would get in my head and ask myself all these questions, like, ‘Why couldn’t I do this?’ At the same time I would tell myself it didn’t matter. She was giving us the greatest gift, and I just wanted them to get here!”

“Overall it was a very beautiful thing, and now that I’m on the other side, I wouldn’t have had it any other way. I’ve always believed that things happen the way they’re supposed to happen, and this is how [our babies] were supposed to get here,” she continued. “I became really close with our surrogate, and it was her first time doing it so we kind of went through everything together. When the children were born, I wanted to make sure she was OK and she wanted to make sure I was OK.”

“It was a lot of navigating through emotions and respecting that she had a connection with them and trying to be really honest about how I was feeling. Ultimately, I realized that I’m very fortunate. I’m grateful. I’m a different person now.”

Wiig noted that she and Rothman wanted to keep the surrogacy process “private for as long as possible.”

“It can be the most isolating experience,” she explained. “But I’m trying to find that space where I can keep my privacy and also be there for someone else who may be going through it.”

When asked how she feels looking back at that time, Wiig said, “I wish I had talked about it more and asked for more help. There’s such a support system out there!”