You have extensive enlargement of your left atrium, and quite possibly some enlargement of your left ventricle (?). The former is the most worrisome because it usually leads to mitral valve prolapse, and that CAN cause AF. It also works the other way around: AF can lead to atrial enlargement, and at the same time collagen deposits, and fibrosis, and those can cause mitral valve prolapse.
I'm sorry to see that your partner died when neither of you could say a last goodbye, although I guess dying in her sleep beside you is a pretty decent way to have it all end considering the other myriads of ways possible. And no wonder you lurched into AF at that time.
I would counsel you to consult a really good, busy, and experienced electrophysiologist and have an ablation done if he/she thinks it's a good idea. You really want your AF to stop so that your heart can commence at least some reparation. It has been established that an enlarged left atrium will often reduce in size substantially once it is not under the stresses it experiences when being inflated all the time by the powerful ventricle below it.