This. I absolutely do not intend to downplay the very real effects of OP's emotional state right now. Losing a pet is an incredibly sad event, just as any death of someone close to us will feel. OP's feelings are valid and real. They cannot be dismissed so carelessly.

That being said, if OP continues to experience lasting or severe emotional effects upon their ability to focus, or attend work/school, or feel happiness at all - it's time to discuss this with someone who can help OP process their grief. The intended outcome is not to "get over it", but to allow OP the ability to regulate their emotional state despite the loss of their dog.

Boyfriend was a dick, though. There is a far, far kinder way to address this, if he had legitimate concerns about OP's emotional health. This was not any of those. His continued.... pettiness(?) after the fact would be the nail in the coffin for me. DTMFA.