Depression. Of others. i need help!

I am in depression.I have a very unhealthy life style.I hardly do any work.I have resigned from my job and currently I just sit and keep talking to myself or keep on imagining something about future which may or may not even happen.I liked someone and that person loves me badly but my parents are against our marriage coz of caste issues.They chose someone for me without my consent.So I met that guy secretly we had a good bond and eventually I decided to move on.Everything was working well until I told my ex about the the guy I am talking to.He(my ex) supported me and he said he wants to meet me one last time.We met and from that day he has become a lot insecure.Now he is not willing to let things go.I am now stuck with 2 people.I have become close with the new guy with whom I am about to get married in few months and still I am going crazy thinking about my ex.I am not able to handle the pressure.I often have panic attacks,headaches,chest pain. I am normal infront of others.I need help