It sounds like she hit the side of the Tesla which would indicate to me that your wife thought she had room, tried to come over but ultimately didn't have enough room to merge. If the Tesla had hit the back of your wife's car, I'd be more inclined to blame the other party.

As was said, spin the story as well as you can but I'd be surprised if they end up siding with you on this one. And unless they assign blame to the other vehicle, it really doesn't matter as far as your future insurance surcharges and paying for damage to your vehicle is concerned.