In my opinion it’s totally not worth trying to get back someone who used to love you. However I can understand the pain you’re going through. I’ve made a few posts on this topic here;
Try the first one, I’ve posted the link to the ritual there and in case you don’t have any spirit link you have a great suggestion on how to make one in the same thread. Try that one and then follow the second link I’ve posted, the instructions are pretty clear. So far I’ve been very successful with lord Sallos though I’m not there yet, but then again I’m concentrated on specific person and in that case it will take a bit longer than having someone appear from nowhere. However, evoking Sallos doesn’t mean he can give you someone back just like that. For what I’ve gathered the point is to possess someone yourself, mainly your personality, traits, intelligence and so forth.
If you do try to evoke Sallos do by all means take steps to improve yourself. How you do that is up to you, be it by evoking other spirits to empower you, working out, socialising more and trying to learn how to be more charismatic. It’s very unlikely that the person you’re trying to charm will far for you if you’re old, fat and poor. There must be something on you the other person finds attractive. Figure out what that is and work on it.