I just had a big wake up call to realization...

I was reading a post on here about frineds having sex with each others significant other and I just went into a trance... my boyfriend and fiance of 3 years...we were having relationships trouble...I drove him 6 hours to pick up his vehicle only for him to take off the next morning to see another girl 5o0 miles away...I realized...he doesn't love me like I thought he did...like I loved him...He told me how they "border line made out"...how could he do that and not think about me or run out in fear of hurting me or caring about my feelings...I am not perfect in the relationship either...and even today I was trying so hard to fix us...when he moved back home 3 hours away from me and told me he didnt have the money to come see me...a 200 mile drive but he again went to see her a 500 Mile drive one way....I left him a year ago because he chose video games and would rarly even talk to me...I saw someone at a party and he kissed me I cried and locked myself in the bathroom and all I wanted was him...how can he make out with her and not feel bad...not cry...idk how to cope anymore.I really thought we could try...just once more but this will never leave my head...I know where I really stand in his heart...I'm just...stuck.He was my first love.my first kiss.my first intimate partner...my first everything and the first set of beautiful brown eyes I got caught up in and I know I need to pull myself out of this and snap into reality and see the pain he put me through.If I am abke to stay away...this will be the hardest thing I ever have to do..knowing one day he will get married and because of me (giving up on us after this) it won't be me...his kids won't be mine he won't fall asleap next to me every night and thats something I Never ever thought I would have to go through...are we just young and dumb and maybe we can recover...even though what he did hurt me more then anyone will ever be able to see or know or is it time to let go? If its the last thing I do...picture from the first time we ever saw eachother...at 15 and 16 years old...we are now 18 and 19

I also just went through a miscarage with our first baby at 5 weeks.I need his support the most right now and we are so distant from eachother...it hurts.