I cant tell her he's cheating

So I'm an ultrasound technician and work in a hospital. Last week I got called to another partner hospital 45 minutes away from my original one because they had no ultrasound techs turn up.

I went and started my usual day, I was scanning woman for their 20 weeks scans.

I'd been there for 6 hours and hadn't had a break because we were so busy. By the time my last patient was due to come in to the office I was knackered and hungry and just had enough.

My last patient walks in with her partner following behind her and it was my best friends husband who was meant to be out of town working that week. He has two boys with my best friend, the youngest being 18 months old!

To say I was shocked was an understatement, he looked just as shocked and didn't know where to look. I probably stared daggers at him the whole time we were there.

As I was scanning her I was asking her questions like 'is this your first baby' she said it was both their firsts.... hmm ok then.

I then asked 'how long have you been together' he was so quiet through it all he didn't say a word! She told me they'd been together 2 years!!!!! Wtf!!! I just smiled and carried on.

I told them they were having a girl and congrats... then I told them to go wait in the waiting room for me go fill out their paper work.

I seriously don't know what I'm meant to do. I can't tell my best friend because I'd lose my job due to patient confidentiality, I rang her that night and asked if she was ok and she said she was struggling since he had been away for work... I was just silent.

Is it worth losing my job over? I just don't know what to do...

Edit- hey guys, thought I'd explain a bit more. They've been together since they were 17, we all met at school.

We're all 34 now. She comes from a wealthy family so I have no issues with her supporting her self and her children. She relies in her husband for mental and emotional support, this will break her heart.

I asked my superior about this, I asked her what I can and cannot say. She said due to certain conditions I unfortunately can't say anything. It could all fall back on the hospital and the lady can sue us.

She did advise me that maybe I could hint to my friend without telling her anything. That maybe I should say things like 'Have you tried calling ... whilst he's at work' and 'have you met any of his co workers, ring them If you can't get hold of him whilst he's working'

So I'm going to do that, but due to social distancing and my husband and I being key workers, I will ask her over FaceTime.

I know he's home at the moment and don't know when he's next going.

What I'm really confused about and don't understand is, where does this other girl think he is when he's away for 3 weeks at a time?

My husband said it's not worth risking it, we have a family to feed at the end of the day, I love my best friend so much. But my family come first

BIG UPDATE-

I didn't have to say anything!!! So last night I FaceTimed her, she was in her bedroom with her husband. He wouldn't look at the camera or anything...

I said to her, 'lovely can you ring me in 10 minutes, just you, I need to tell you something' she said of course and hung up

10 minutes went by and she didn't ring, I thought that was odd but didn't say anything.

She rang me at 3am!!!!!! 6 whole hours after I called, she told me he told her everything... She asked if I was going to tell her and I said I was going to tell her everything excluding the woman so my job wouldn't be affected. She was crying hysterically and told me she's kicked him out and she's text this other girl to tell her she's welcome to him!!!

This girl rang her straight away and they spoke whilst her husband was crying in the background saying he wanted his wife and family and how this other girl was a mistake... My friend was devastated obviously. She said this other girl couldn't stop crying either!

She called her parents and they're hiring the top lawyer in their city for her right after they've rung all the offices in their city so he can't get legal help from them!

I'll update if anything else happens but for now he's finally told her and they both now know the truth... He's a horrible man!