did he think you could read his mind and know he wanted an open relationship..you deserve way better than this kind of treatment. you did everything you could for the relationship so there is nothing on your part to regret, let yourself be sad and slowly but surely you'll move forward and wherever you both stand with each other after this, he's broken a trust that can't be regained forever and that's all his fault, for technically cheating/making excuses for it, you can't call it an open relationship if one person wasn't made aware. I wish you strength and happiness

him not being able to value you and see your worth is not your problem, someone right and better for you eventually will, and you'll be so glad later that things with this person didn't work out the way you wanted