After 3 weeks it feels like we're going backwards...

I [36M] discovered that my wife [34F] had spent a week sexting and sending explicit pictures to a guy she met on a hookup subreddit.

We've been together for nearly 15 years and have a young child. Our lives are very intertwined so separating wouldn't be straightforward for either of us. We have also both built up a lot of resentment towards each other over the years and both thought that the relationship was over, especially with how bad things had been over the past 6-12 months.

When the affair came out a few weeks ago, there was the inevitable arguing but we had the argument by text so as not to argue in front of our child. It felt like we concluded that things were done but then I sat there and realised I actually wanted to fight for our marriage. So I went and found her and we talked face to face. Things calmed down and we both agreed that there were still a lot of positives and that we wanted to try to save the marriage.

For the first few days she was very open about what she was doing and who she was messaging, despite me not asking for much. She quickly became frustrated with doing that, even with things she'd volunteered herself. Without saying anything she changed the passcode on her phone and later told me she wanted to reclaim some privacy because I had violated it by going through her messages, chats, etc.

As for the AP, she initially said she couldn't just block him because he knew too much personal information. I told her that whatever she ended up doing, I just wanted her to be transparent about it. A few days later she had said nothing and so I had to ask - she said that she had decided to just block him. Whilst I can understand not wanting to bring up a painful subject, I had been more than clear that I wanted her to be open about it.

What worries me most is that it feels like we're slipping back into our old dynamic. We had a really positive first week (albeit emotionally agonising) and were talking constantly, being affectionate, etc. and it genuinely felt like a reset. Now we're talking much less and she's retreating back into her bubble, our conversations feel very one-sided.

We've started couples therapy and have had a few sessions but it's still early. One of the biggest issues is that she says she still doesn't know what she wants. She talks about feeling "trapped" and says she's still uncertain, but she can't really explain what that uncertainty means. It doesn't seem that she is any less uncertain now and she mostly refuses to talk about it.

My best friend told that me that he expected her to be in "full grovel mode" right now - I don't necessarily agree with his phrasing but he has got a point...

I know it's only been a few weeks but am I being stupid for trying to make this work when she still seems so unsure? How long would you give things to change?