You deserve that ring - what a miserable person to ask for it back when he gave it to you. Hope you told him where to get off.
Best if you don't have to see him because it keeps the grief alive. Are you sharing custody of the dogs?
The kind of gut-wrenching grief you're experiencing does get better, but if you want to speed up the process challenge yourself to do a few things to help. Walking, lovely music, writing poems, something with friends, a massage; just do it, even if you don't feel like it.
One day you'll realise with surprise that your mood has lifted. It's hard work but there is a pay off.