I've had similar experiences with mine who I have been with for 16 years. She is painfully aware of what these things cost, and the ones she has broken (oddly enough, two engines, like you), she really felt bad about and was pretty upset; far more than I was. While these two locomotives were two of my favorites and most expensive (funny how wives have that sort of luck), in the end, what's worth more? Your treasured bras locomotive or your wife? I got really p.o.'d once when she snapped the switch stand off a Lionel Fast Track switch and really felt terrible about the way I acted about it (she's clumsy and doesn't look where she walks often, and I had it set up on the living room floor testing some new equipment when I switched from HO to O), but really felt like a tool afterward because A) it was a toy after all, B) I can always get another switch, and C) she deserves so much better and D) she's worth more than my train collection.
As for the broken locomotives, one, was cosmetically repairable but would have needed a new frame to operate again (epoxied the frame back together) so, it was a static display after that (SP Olympic SD40-2), so since it was going to be a shelf queen, she asked me if she could take it to her office and have it for her desk, which I was happy to do, and the other, I was able to repair, but even with bent step wells, and mismatched paint, It reminded me that nothing is perfect in life, but though it didn't look 100% anymore, the engine still ran like a Swiss watch and rarely ever let me down, just like our relationship so it was kinda symbolic and oddly, made that engine that much more special to me. I eventually gave into my friends consistent begging, and sold it to a friend of mine who is into the same shortline and used the money to buy my wife the ridiculously expensive bowling ball, shoes, bag, etc. she wanted that year for Christmas, so it all comes full circle.
By the way, by not going bananas on her when those two (really three including the switch) incidents happened, now that I'm in O 3rail and On30, she has gotten involved almost as heavily as I have and has her OWN trains of both scales and is even more anxious to build a new layout as I am. She's also heavily involved in the WP RR Museum as a volunteer where I am a Director, and our CZ "Silver Plate" Dining car is her baby. She even did the footwork for Atlas when they were engineering their O Scale CZ Diners, and they sent her their pre-production sample as a gift. In the end, trains are just trains, they come, they go, but a great wife like mine is nearly impossible to find. I wouldn't trade mine for all the trains in John's store.