Why does my heart feel likes it is going to explode or fall out ?

Why does my heart feel likes it's going to explode or fall out? To get a better understanding of what s going on, here s how it started. I found out my fiance was engaged to someone else. I started talking to his other fiance on myspace when I found out I was pregnant (I was actually happy when I found out) and whatever. He left me for her and I ended up losing the baby. Ok now. The problem is, whenever I would get a message from her my heart felt like it was about to explode or something. I would start getting dizzy, confused and my chest would start to hurt. It s been roughly about 4 months or so since all that happened and I m still having the same problem s as far as symptoms go. I can sometimes feel my heart beating and I get a small pain in the highlighted areas in the picture provided. I m 18 and I was born without a heartbeat. I don t know if I have a cardio disorder because my parents never took me to get my heart checked out. I don t smoke, drink, or do drugs. I m on birth control pills. http://i152.photobucket.com/albums/s197/chilangochingon26/ribcageinverted.jpg I don t drink energy drinks, coffee or tea. Oddly enough the feeling is what you would feel if you had too much cafein. And I m already over the bad ex so it s not like that. I already have a small ceremony planned for what would have been my baby s birthday. I m ok with all the bad. I just want to know why it hurts physically in the parts highlighted in the picture provided. What I mean by feeling it beat is that I can feel it as though I d have been running for a while. I can feel and hear it beating sometimes.