Guard my heart.....

So I've heard over and over since I've been saved to "guard your heart". and I never really understood it. I mean I've built this WALL around my heart...... but that's not what it means. I realize after listening to a radio broadcast that I not only need a wall...... I need to keep my fears and past hidden as well. Hidden from boys. My past is something that opens the door for pain. It opens a small portion of my heart to those who I tell. I need to keep some things... which I have. There are parts of my past/ex-fiance that NO ONE knows.... that I haven't told anyone. I don't know if its because it's too personal or if it's just because I'm ashamed of it. BUT I realize that I need to NOT tell..... I mean yeah I can tell that I have an ex-fiance.... but I don't have to explain. My worry is I cannot really share much of my testimony without telling at least that he was a con artist. and That I ran away.... So do I not tell my testimony? Or what? Is this was actually "guarding my heart is". If so It's too late with this new boy...... I've told him about my past. Uh I'm stupid huh? I need to keep my big mouth shut. I found myself today telling my friend Miranda things that I never have told anyone.... I actually had some old memories that I've forgotten about come up. I don't know if I have some how managed to block these memories.

How do I guard my heart? How do I not let a guy know too much about me? Should I just keep everything a secret....? I don't know. I'm confused. I need help!! I'm 18 years old. I've done my "fair share" of dating.... I mean..... but never dating as a Christian. I was always.... I don't know. I mean as bad as it is...... If I liked a guy I would straight up walk up to him tell him and if I was at a party I'd just make-out with him..... if not more. and Sometimes never even knowing his name. My ex-bf kyle..... I just was friends with him a WHILE and we basically "dated" without the commitment before he made it. and I gave away my heart..... and alot more...... and than my ex-fiance Thomas..... I met him at a club... somehow managed to becoming bf and gf....... and next thing I know it was like we had been dating a long time... and I gave more than my heart to him way too soon as well.... than we got engaged and ect........

I just don't know how to date anymore. With my past........ why would any decent Christian guy want a girl with my past. Most of them have a list of what they want..... virgin is usually at the top! I disqualify myself right off the bat. plus It's not like I'm some model.... I don't know. will I ever get married? ever be able to fall in love again? ever meet a man that will love me for me and for all the mistakes I've made and continue to make? Ever a man that will see past my appearance and see my heart? Am I even able to let a man see my heart if I'm guarding it? It I have this wall of protection? I don't know

Help..........