Feeling lost and worthless after a horrible breakup

I had been with my ex boyfriend for almost a year and boy we had a bumpy ride the first few months of our relationship but after I spoke to him and told him how I felt about the way he was acting, to my surprise he actually changed...He became the guy I knew he’d be...genuine...sweet...he was always there for me, and every time we were together it’s like time stopped and it was just us in the world...Everything was perfect. So eventually he enlisted into the Air Force and left in November...I wrote him often and thought about him even more often...He writes back and tells me he misses me and that second I felt all was good. Eventually boot camp ended and me being insecure I thought he’d leave me but he didn’t...he picked up our FaceTime sessions and all like it never stopped. He would’ve been my first Valentine...and he knew it...he bought me a gift I MADE him a special gift...That Thursday before V-day All was fine he texted me “good morning baby” and all. My package for him was expected to deliver that day so I was excited for him to get it...Then suddenly that same day out of the blue he just broke up with me and was so heartless and careless about it...I BAWLED I begged and I pleaded. I told him that he was my only blockage of my depression and insecurities because he made me feel so good. Instead of having a heart he blocked me on everything as if I did something when I KNOW I didn’t... now my depression is back even worse now and my insecurities are 10x what they already were...I just don’t understand...I gave my all for him...When I came out to my mother in the past I swore to never get too serious with a guy because it wasn’t what I wanted at the time but I swear I would’ve married that guy if he would’ve asked...and that says A LOT...I’m so hurt and feel so lost and worthless...half the time I wish I didn’t exist...