Hi Lisa,it's truly awful isn't it,most of us on here have felt like we're dying at one point or another,so you're not alone,palpitations are quite common as are your other symptoms,my anxiety comes and goes,some days I'm quite sure I'm dying,on my good days I just think,oh you silly moo.
Like clkd said look at some of the stuff on here,it's definitely helped me.good luck