I want to marry an engaged guy.

We both love each other. But, his family insisted him to get engaged to this who he liked years back, all this happened as urgently they didn't wait for him to land in Karachi or for the girl to come to Dubai. Everything got fixed over calls. He doesn't want to marry her because she's not respectful and abuses him. That's why he gave up trying on her. And chose me and was stuck up on me, he even started his business so he could permanently move back to Karachi, else my mum had said clear No for him because she doesn't want me to leave Karachi. Now, that she knew he liked someone else, she came after him as her father and his brother are friends in Dubai and she portrayed (from Karachi) as if he's still interested in her and he must marry her now. He tried to resist, this matter extended that his father (from Malaysia) asked his brother to throw him out of the house if he wants to marry me over that girl. Everyone made it the matter of their honor all of a sudden that they can't say no because at one point he liked her  He left home and wandered for 2 days and no one called back. I told him to go back and do as they please. He cried his heart out and went back to say Yes. We completely cut off. Then he came back crying that he can't do this. This girl is only satisfying her ego and he is not happy with her. He wants to be with me. I tried to convince him for her for 4 months on and off as we kept discontinuing talking. All because, he comes after me crying and tries to convince me to wait for him till July so he can call this commitment off and convince his family for me and until then I'm not supposed to meet any guy for marriage proposal. It shakes me to my very core how can I let this happen to any girl (had it been me) or his family will be dishonored or won't accept me, or will I ever be happy if I support him now. I'm a very cowardly person who's stuck with "what if(s)" all the time. I pray for his happiness and sabr but can't convince myself to even ask for him from Allah. I'll only pray for like a few good minutes that everything goes smoothly, no one gets blamed or dishonored or hurt.. and we can be together happily but within a minute it seems like I'll end up badly. As if my prayers are not enough, something is missing and I'll regret asking Allah for him.  I feel so hurt, lost and helpless. I know I must turn to Allah in all matters. I should trust Him with this matter as well. But I can't seem to let go off him or ask for him either. It feels like a sin. But what should I do? Praying is the only resort I have.. but is it haram to ask for him to be mine in every good way possible,? Or is it just selfish and harmful? I need something concrete to set my belief here. I want him but I don't want to hurt anyone or myself either or break his heart. Please guide me. Am I allowed to pray someone who's engaged somewhere else. Note! I have asked him many times if I should ask for him in prayers and he has happily given me his permission. But many times, when we start to get back together he seems distant then tells me that that girl had contacted him and said him not to break this engagement and had threatened hik about my safety. Which he confirmed that she had sent a guy to keep an eye on my place. And he had to give in and get distant from me to protect me but he didn't mention this to me so I don't get scared. I do believe she gets screenshot of our chats by blackmailing him that's why he gets away from me. Andddd most importantly, he always comes back crying and begging to me to get back together with him and wait for him. From that day till we completely cut off, I puke persistently, I have got every medical test done and everything came out clean. Even the doctors are shocked that i have been vomiting for so long now and my internal body have no signs of it at all. And the day we will stop talking, mainly because he'll get upset with me over dumbest thing, (then clarify next time that she had contacted him) my vomiting will stop as if they never happened. I want to be with him, we love each other so much. But these things and my fear everyone else keeps me from asking for him.