Like I mentioned, I have encountered this situation before.
The last time was when I was working in Ladbroke Grove, at St. Charles Hospital, and we had just had 'bike boxes' installed.
My Marin Rocky Ridge was in the box and one of the nurses called me to tell me someone was trying to get into the box.
I ran round and confronted the teenager, who I recognised from the gang who hung out locally, and told him if he wanted a bike I could sell him one. He held his hacksaw blade up as if it was a knife and I lost it. I kicked it out of his hand and pinned him down on the tarmac. The security guards arrived and pulled me off him, and he ran off.
Once I had calmed down I realised he was on film and so was I assaulting him.
I asked them to leave it at that, realising I was possibly going to come out losing a lot if it went further.
A month later I was at the chippy near the canal on Ladbroke Grove. I laid my bike against the low window as usual so I could keep an eye on it while I got my food.
A tall guy came in, stood behind me, I went to bob around him to see my bike and he body blocked me.
I felt something was going down, and pushed him out of the way and my bike was gone!
I ran out and round the bend down the lane, no sign of the thief. Guess he went the other way.
But he had been seen.
I called the Police and reported the theft, they interviewed two witnesses who named the thief.
Same kid who had been filing through my wee padlock on the bike box.
Went to court and everything but nothing happened.
Got to know the kid though, and I ended up helping him out a few times and we are still friends.
If I had punched him and kicked him instead of disarming him and restraining him I doubt he would have decided not to steal my bike when he got another chance, but I am certain we would not be friends now.
I have taken a scaffold pole to a group of teenagers in a forest in Eastern Europe when it seemed they intended to rob me and my gf (at the least...).
No one will ever get a free pass to abuse me or mine, but I will always keep cool as long as possible.
Your mileage may vary.
I understand the feeling of being violated, but try to keep some perspective.
To you and me our bikes may be objects of desire and love, but to others they may just be objects.
Don't one day say it is just an old bike, and next act like you would go Rambo on anyone who might try to deprive you of that old bike.