Metoprolol Succinate 25mg

Hello I was just prescribed Metoprolol Succinate 25mg and I am afraid to take it..I have anxiety and palpataions just thinking about it,im afriad of the side effects,is anyone on this and what should i exspect? i know everyone is different,but still..just got to know..I suffered from palpataions and skipping for yrs,also i have mitral valve prolapse since 2008. i had a 30 halter moniter on last year and the doctor said he saw alot of palpataions but thts it..he didnt prescribe me anything,then last week i wore a 24hour moniter and said my heart beats to much,,and prescibed me Metoprolol..I knew my heart got worse of the year,i could feel it of course,so i wasnt that surprised..last thursday my heart had palpataions for10hours straight and my heart would stop beating for about 3-5 seconds,that really freaked me out..i use this app on my iPhone called heart rate and it works pretty good.that whole night my heart was not beating normal,i had my mom and boyfriend use the heart app and there heart was fine,when i did mine,they thought i was playing some crazy joke,which i wasnt..so then i decided to take a Xanax and shortly after i felt better,the rythem was better,not great but much better..So Anxeity will make your Heart worse and stress,try to relax,maybe meditation cds,im gonna give that a try myself,also i have Attacking Anxeity CD's by Lucinda Basset,and they do help,i havent finished them yet.also I have hypothyroidism too,taking pills for tht as well and for acid reflux and got something new for my digestive system,im just a mess :( im only 35 and i never smoked,i dont do drugs and i barely drink,im 5'9 weigh 137 ..people always say how young i look,but inside i feel like im 75,with all these problems already..my grandmother dosent even have these problems,however my Aunt does and my dad has heart problems..PLEASE tell me your problems and what the doc put you on and experiences from that..thank you