He WAS assaulted. He needs to know that he was not at fault,
This won't wash with most men, and with a guy suffering guilt from the given circumstances, I would very much suggest this line never of thought never be brought up.
By the way, fault doesn't exist - influencing circumstances and personal responsibility for ones action does.
Personally, I'd approach from this angle :
- You were in X situation, with Y & Z circumstances beforehand
- she turned up and surprised you, and she did A + B (and you may have done C), which put you in position D
- You f##ked up, and chose to E
- as a result you feel guilty (and possibly F& G)
- You think H&I about your brother
- you feel J&K about your sister in law
Is any any way you can make it better?
- will telling your brother make it better (the answer is No!)
- will anything else make it better (the likely answer is No!)
Live with the consequences (because you're stuck with them), admit you have weaknesses, admit you make mistakes, get on with life, and build who you are into someone you can be proud of...even while you may retain some sadness for the mistakes you made - you're human.
Now...what are you going to do about our love life? (the answer should be something along the lines of - get on with life, and focus
on making it better between us...even if that doesn't happen straight away).
Just my thoughts.