what went wrong?

the inside of my heart feels heavy as if a brick is tied to a rope weighing it down. whenever i breathe in and out it feels as if its under water, compressing it down. my head feels light. but not a good light. my hands feel cold, numb. the tip of my fingers tingle a bit. it doesnt feel normal. i can feel my heart beating through my chest. boom. boom. boom. faster than usual. like its racing itself to make me feel this way. i feel uncomfortable. my mind goes to what made me feel safe back then, go back. just do it again, it wont hurt. i snap out of it. whats wrong with me? "just do it". 
i need to get rid of these thoughts, stop thinking those things when things go bad. no one normal thinks like that. are you sick? i think to myself. everything about me is wrong, just wrong. i want to feel that rush again. but i stop myself before i do anything bad. its horrible, stop thinking it. just stop it. think of something else. so much anxiety, so much pressure. just so much SHIT. i want to run away, i want to non-exist. i want to NOT feel anything. but i feel so guilty saying that because i remember the happy times, the people who care. but truly, at this moment. i want to get out. i want to escape. i dont want anything. why does shit have to be so hard? i ask myself. what went wrong?