Ex wife filled a claim on engagement ring with out my knowledge

She claimed she “lost it” but after it was paid out she found it. The sum was $15,000. 60 days after it was paid, her off and on again boyfriend of 4 years purchased a house 1.8 miles from ours. We are now divorced. They are now engaged. She has returned the ring to me. After some investigating I’ve discovered what she did. She contacted the insurance company and informed them she found it. They now are exercising their right to recover the ring. Can I sue her for what she profited off of the ring.