He would tell me he loved me and he wants to marry me but then he’d go and sometimes ditch me for his friends, like tell me we’d hang out then go to his friends instead. I know this may not seem like a big deal but it happened a lot. He also drank everyday and I didn’t know if that was normal or not. He’d drink so much sometimes he’d get sick and have to go to the ER.
No, that's not normal except for those who are addicted to a substance, in his case alcohol.
Now is a good time for you to take a giant step back and find some help for yourself to discover why you allow him to treat you this was. A toxic relationship has no place good to go. Is this the kind of person you want to marry and spend the rest of your life with? He brings nothing to the relationship, you will continue to get hurt until you say "enough" and realize that you deserve to be treated better than this.
Take a good read around, I think the sticky threads at the top of this forum might be a good start for you to read and learn that how you treat yourself is what matters here, more than even how others treat you.