I ran outside and not on treadmill…

After running almost 2 months now in my gym on treadmill I decided to do my long “easy” run outside which was 13km/8miles, and it didn’t go as planned at all. My pace was off first of all. I started running so much faster then I should have. My heart rate was through the roof (160 average) and also on top of that I suck at running anyways so my average pace was around 7mins a km or 11min mile pace anyways. To summarise I felt so bad, this made me question myself and these past 2 months of work. My pace is still dogshit and my heart rate is all over rhe place. I’m not good at anything really, I don’t stand out in anyway but I push everyday to be better. Sorry I just had to get this out of my chest, don’t have many friends to talk and I ain’t got many people to help me with this. My question is, is this normal, how can I improve and please if you can give me some valid tips. Thank you!