Doesn’t sound like it is right for you, it sounds like you want things to be exactly on your terms. You need to have a calm conversation with your wife, explaining what you had hoped for and ask her what she wants. She may have just taken the suggestion and when an opportunity presented itself went along with it to see how she felt.
It could be that she didn’t want to take things any further and didn’t mention the encounter in order to pretend it never happened, worried you would get upset, seems she might have been right.
It could be that you have sown the seed in her mind that she would like to experiment with other people but is uncomfortable with doing it on your terms. I f this is the case, you will have to agree with each other if the two of you are going to continue with a ‘normal’ exclusive relationship or if you are willing to cut the head off the green eyed monster and give her the freedom to do things her way.
On the other hand it could just be a misunderstanding that she thought she was doing something that would excite you but didn’t.
No matter what the reason, do not get mad with her, be kind and discuss it like adults. If you get mad with her and she was trying to please you, she will hate you for putting her in the situation and then berating her when she got it wrong. If you get mad with her and she has already decided she wants the adventur, she may say stuff you and do it anyway behind your back, and there will never be any trust between you.
Most important, if you have already argued about it, apologise to her for overreacting and tell her how important she is to you and that is why you got upset, then offer to have a proper discussion about it, and make sure you listen carefully to her point of view. Don’t just dismiss anything she says, try and understand her point of view and explain how your expectations differ.