Finding a new boyfriend would be the first and most important thing to do. Letting him know why you left him would be an important part of the equation (I suspect he’s exhibiting other inappropriate behavior, so this confirms it’s time to leave him). Keeping such a boyfriend would be nothing less than a sad continuation of victimhood for women and reflection of your low self-esteem.

Getting the parts back to the owner would be the second and appropriate Karmic thing to do, either by your boyfriend doing it or by your hand. If there is any chance your boyfriend will be hostile toward you in any way, do not take returning the parts into your own hands.

That you chose to anonymously confess your boyfriend’s criminal behavior and seek input is a great step. Continue that path by leaving your boyfriend and elevating yourself, and if safe, ensuring the parts are returned.

By doing so, you might turn this into a positive event: you elevate yourself, the owner gets the parts back, and your boyfriend just might learn something. Win, win, win.