As painful as this is, your problem is not with the woman. Your problem is with your own insecurity and with your questions about trust in your relationship with your husband. It doesn’t matter what this woman posts. It doesn’t matter that she can’t move on. That’s her problem, not yours.
It makes sense that your husband doesn’t talk about someone he had a flirtation with. He chose you, not her. I’m sure it hurts him that you don’t believe that.
For that reason, I think you and your husband need to see a couples counselor for a few sessions. The two of you need to air out any issues of trust that exist between you. Without trust, your marriage will fall apart. Your husband needs a counselor’s help to find a way to reassure you that you will accept. You need a counselor’s help to find a way to freely give your husband your trust.
You were wise to write to us here at PsychCentral. If you continue to monitor this woman’s app and obsess about what it might or might not mean, you will erode what looks like a promising marriage. I’m sure you don’t want that. The fact that your husband gets upset with you suggests that he doesn’t want that either.
Please follow through and make an appointment with an experienced couples counselor so you two can resolve this issue once and for all.
I wish you well.