On a recent afternoon, a doctor walked into Ami Brown’s chemotherapy treatment room to find the Alaskan Bush People matriarch’s husband Billy holding his wife’s hand and resting his forehead on her wrist.

“The doctor came in and said ‘You’re giving her so much support’ and I said, ‘She’s the one holding me up,’ ” Brown, 64, says of what it’s been like watching Ami, 54, battle lung cancer over the past few months.

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In his only sit-down interview since Ami’s diagnosis earlier this year, the reality star opens up to PEOPLE about caring for his wife, deciding to relocate his family of nine from their homestead in rural Alaska to Southern California, and how his seven children are coping with their mother’s diagnosis:

It can’t be easy to watch your wife in pain.

She’s the strongest person I know, so if she’s saying it hurts, it really hurts. She tries to hide it from everybody but four or five times a day she bends over like a baby and cries. She bends over and tears run down. She put out seven babies without a grunt. I’ve always had a lot of respect for Ami, but I’ve got a lot more now. She makes me feel like a wuss.

What went through your mind when the doctor told you her diagnosis?

The doctor came in and was very straight forward. I appreciated it. He didn’t mince words. He said, “It’s cancer. And there’s no primary but we’re gonna call it lung cancer. At least 3B. It’s in both lungs, in the middle and sides of the lungs.” We know if it’s in the brain, it’s over. And if it’s in the stomach, that’s bad but this cancer can be right where it is and go anywhere. It can go to the brain. It hasn’t traveled to any other organs, but that’s what they’re saying is next. Any time we talk to anybody, it’s bad news.

Was it difficult deciding to pack up and leave your home in Alaska?

The kids really made that decision. We saw Ami slow down so fast. She started out 128 lbs. and she dropped to 89 really fast. Last winter was really hard on her. [Our son Bear] got really mad one day. I was pretty bad and mom was pretty bad and he started right then, “How long are we going to do this?” Once we knew what Ami had, Bear was adamant. We had talked about it before and when we sat down realized and made the decision, it wasn’t like it came out of nowhere. We’ve always told the kids they don’t have to follow our lives. We moved out there because we wanted to. They just came along and we have been so proud that they wanted to stay with us as long as they did out there but it was time. We had to make this move to do what’s best for Ami.

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Do you feel stifled having to live in a city now?

We talk a lot about wanting freedom in our lives. That’s why we moved out there. But the freedom is all right here [with Ami.] Freedom is having a family so strong and so with you that you can get through anything. Freedom is being with your family. I can’t lose that. I can’t live without her. I can’t lose her. I just pray every day that we’ll get good news.

When you’re caring for Ami at home, what does that look like?

It’s what we’re doing right now [in her chemotherapy treatment room at the hospital]. I just sit with her. We sit and talk and the guys, they try to not all come at once so it’s not overwhelming. But they come by. I’m never more than 10-feet away from her. I don’t sleep. I don’t want to lose that time with her. I’ll stay up just watch her breathing while she sleeps. Eventually I’ll fall asleep watching her and then Bear will come in and sit with her until I’m up again.

How are your children handling the situation?

Some of them don’t want to admit that she’s so bad. They’re all trying to get through it as best they can but no one knows what to do. I do what I can. This is really hard but this is also the strongest our faith has ever been. Our faith is giving us hope.