Lonely and worthless

I hate sounding low, although the majority of time when alone low is how i feel.

I feel lonely and worthless, Although I am only 18, All of my friends have settled down and most have children, that really hits home and makes me re-evaluate my life. I hate feeling alone, I never seem to attract the right men,
My last relationship was 4 months ago in which i left my violent ex(which i posed a fourm for) he has still contacted me but i still do not reply.
I have seen that he has now settled down(by his facebook) Although i dont feel jealous of the girl i feel quite in turmoil as to how he is representing her and showing her off to everybody, I mean we lived together, i done everything for him and his family, even things i didnt aggree with just to keep him happy but he NEVER showed me off or claimed to be in a relationship to alot of people
this hurts me alot...I feel as if i was just there for sex and to serve his family...I feel like crap...my self-esteem has lowered even more than it has.
Alot of people have told me that hes only showing her off because he still feels rejected by me so he's trying to hurt me, which i agree with, i know his personality but he is so sly in trying to contact me behind her back but i know he is hurting too.

I wish I could just rewind time and erase chapters of my life.

I always seem to attract the wrong type of men, ones that always try to change me or just lay theyre hands on me
Lately I have been throwing myself around, I just dont care for myself or life anymore but I regret this, I regret that despite people have hurt me to top it off Im hurting myself, Im adding to my pain.

Im at that stage where I just want a stable relationship someone i can trust, someone i can love.

I just dont want to hurt anymore