AITA for refusing to help my friend after she cheated and expects me to cover for her?

I (26F) have been best friends with Sarah (25F) since we were kids. We’ve always been there for each other, through everything. But recently, things have taken a turn, and I’m honestly not sure if I’m doing the right thing.

Sarah has been married to Ben (28M) for about 3 years. Their relationship has had its ups and downs, but overall, they seemed happy. However, about six months ago, Sarah started confiding in me about how she was feeling distant from Ben. She claimed he was no longer attentive and that their intimacy had dwindled. While I tried to give her advice and support, I did also tell her that if things were that bad, she needed to communicate with Ben, not just bottle things up.

A couple of weeks ago, Sarah admitted to me that she had cheated on Ben with a coworker. She was absolutely distraught and regretting it, saying it was a mistake and that she didn’t know how to fix things with Ben. I tried to listen, but I also told her that what she did was wrong, and if she wanted to stay married, she had to come clean to Ben. She cried and promised me she would eventually tell him.

Then, last week, I found out that Sarah hadn’t told Ben the truth. Instead, she asked me if I could cover for her, saying she was “still figuring things out.” She wanted me to lie to Ben, pretend everything was normal, and even go as far as to say she had been spending time with me to avoid any suspicion. I was shocked and immediately told her no. I told her she needed to face the consequences of her actions and that I wasn’t going to lie for her. She got really angry, accusing me of not being supportive and saying I was “choosing Ben over her.”

Now, Sarah is not speaking to me. She’s upset, saying I should be helping her, not making her situation worse. A few mutual friends have reached out to me, saying I’m in the wrong for not helping her. They think I should be more understanding and that what she needs most right now is a friend who’s willing to support her, even if that means keeping her secret.

I feel torn because I understand she’s in a tough spot, but I can’t be complicit in lying to Ben. I just don’t think I can do that to someone who has been a part of my life for so long.

So, AITA for refusing to help my friend after she cheated and expecting me to cover for her?