Why Do I Do This To Myself....is It Real?

After being in a relationship for 5yrs and finding out he had something going on w a co worker.... things were never the same. I had never felt so alone and betrayed.... but after a while he came back and tried to fix things.... to this day hes my best friend but he has no idea whats going on. As hurt as i was overtime i began looking for others to talk and rely on when in reality it was a desperate search to feel loved and have attention. I have always felt so alone and have had people come and go out of my life. I used to be strong but now i just feel beat up and bruised no longer able to withstand the punches :( Ive met people here and there but 6 months ago i met someone i thought was special. We hit it off and he made me feel like no one had in a long time.... But as time went on I saw things that were off... Finding random profiles online... lots of female aquaintances...lies on top of lies...Trust is number 1 to me. And from the start he lied.... he was talking to other girls while dating me, i discovered planned dates, i found out he had taken one out on a few occasions and used to tell me he was working or asleep. He would be the sweetest then take back things he says like i love you... and just change the way he acts all the time constant rollercoaster...It was always someone else... feel like somethings wrong w me or that im not good enough bc the men ive dated look for someone else eventually.... :( im sure he prob slept w other girls but hell never admit it and ill never know... which KILLS ME. Makes my heart and mind race. Like am I good enough am i doing enough to keep things happy? constantly worried. just not a healthy relationship n he goes from saying im not going anywhere babe to i cant take this anymore :((( im still w him to this day... seems pretty one sided because hes never said im his gf in public around friends and family.... like im some dark secret. When he should be proud to say im his :( i honestly dont know what im doing anymore....or why im still trying w him. He has made some changes but with him living an hr away and not seeing each other often makes things even harder. i dont know if hes playing w me or stringing me on because he knows i fell in love w him before i discovered his dark past which ive learned to let go.... but i cant break away....it haunts me... im attached to his loving words and the way he can make me feel...but when im next to him I question if anything is even real and am i just fooling myself trying to find hope in someone who cant give me that...idk. He has made some changes and ive seen them in his patience and openess about things... but am i putting to much effort into something that wont work in the end? how can someone whos hurt you so many times ever really change their ways? :( everything about this relationship scares me....