My wife was sexually assaulted - she kept it from me for months

Between July and October 2024, myself and my wife were going through a trial separation. A story for another time, but our relationship went south quickly over a period of 8 months due to things that happened having a near fatal impact on our marriage (not infidelity). We are back together now, have been for almost 4 months and things are looking up. It needed to happen in some ways.

Anyway. late September (approximately 2 weeks before we reconnected), she was at the family home (I had moved out to give her space) and a maintenance guy (of whom I know quite well) went round to fit a new appliance. She was home alone. As he was leaving, he asked her what she was planning to do for the rest of the day, and she politely responded that she might go to the gym. He proceeded to put his fingers down the front of her jeans, pull them away from her to expose her underwear and then gripped the waistband and pulled her into him before saying "you don't need the gym". She said she froze for a moment before telling him to leave. He did thankfully, before sending her a text message apologising.

She kept this to herself for months because she was a) terrified of him and what he might do and b) how I might react.

She finally broke down and told me about it last week, saying she has been terrified of him coming back, and that he had text her a few times looking for reasons to come round to fix issues with the house, and that she had been making up excuses why he couldn't attend to keep him away.

Obviously, I reacted badly to finding this out. It is pure and simply sexual assault, she was alone, vulnerable and his actions were unsolicited and without consent. She has been scared.

It got reported to the police, and I spoke to the agent who rents us the house, however I am just feeling violated myself somehow, and unhealthily angry. I also feel terrible guilt for not instinctively wanting to hunt this man down to get revenge, but something is stopping me doing that. Is it her wishes? Is it the shock of finding it out and I have frozen, is it the fact we have children we are responsible for?

Something about the whole thing is making me feel like a let down. This happened to my wife and I couldn't protect her, and I have not gone out to find the guy.

Why do I feel like such a loser?