I recently found out that, over a period of weeks, a very close friend and my husband secretly exchanged messages that became increasingly personal and crossed appropriate boundaries, including discussing dissatisfaction in their marriages and some flirtation with her saying she found him attractive. I found out completely by accident after seeing some messages that he'd saved in a shared folder as he was worried about her behaviour, he then told me everything.
Apparently during the contact they both recognised the situation had become inappropriate and attempted to reinstate boundaries and be normal friends, but my friend continued to message and push those boundaries while my husband tried not to reengage. She was increasingly irrational asking why he was ignoring her and then unfriending and then trying to refried him on FB. When I found out I asked him to block her on all channels.
Finding all this out was deeply upsetting, both because of the impact on my marriage and because she was a really close friend who I spoke to daily and leaned on in tough times and I believed I was the same for her, I've always been there for her and supported her. When I found out I tried to act calmly and process everything so didn't contact her for a week, apart from saying I was dealing with some stuff.
About a week later she messaged my husband from a different account and was clearly wondering if I knew and saying she trusted him 100% but needed to know if that was right. I thought it best she knew I knew so I told her but that I was still processing and not ready to talk. She reacted with significant emotional distress, no apology though just saying she loved her husband and he was her life, she sent me some worrying messages about self harm, this led me to contact her husband out of concern for her safety, I didn't tell him what she had done just said we'd fallen out.
He let me know the next day that she'd told him what had happened but had deleted most of the messages from her contact with my husband.
Since then, there has been no contact from her, and I been focusing on my marriage and my own wellbeing.
I'm struggling to get closure though and feel she should have at least apologised, is that unreasonable? It's been over a month now and she is posting a happy life on social media as if she hasn't done anything wrong.