The Result Of Ignoring Redflags

I have been in a four year relationship, there were several breakups in between the longest being for months. I have been through the loss of a nine month baby boy and a lot of other issues. In the middle of our first year together there were alot of "red flags" that i didnt pay much attention to and somehow every time we argue, we always end up patching things up and tried to move forward. He left me when i was pregnant, turn his back on the baby and i, said hurtful things to me, he even wanted me to terminate the pregnancy. I have been through hell with this individual yet still i took him back. i thought it was love, i really did. There was a speculation that he was in a relationship with another woman due to a text message that was mistakenly sent to me, however he denied and ask his cousin to lie for him and tell me he(cousin) was trying to send someone a message from his phone. I eventually ignored and moved on. Later on i saw some questionable comment from this same woman on his facebook page we had an argument which resulted in him telling me he doesnt want our relationship anymore . I took him back when he came begging yet again because i was truly in love, we had a few arguments about this same person a few times after and i still looked past them all. Now a few days ago i attended this party with him and the other woman was there, he spoke to her for a bit and then he came back to where we were standing, i didnt think much of it at first because he would always say thats his "friend" moments later in the party she came over and pull him aside and by their gesticulating i could tell it is something more than he was admitting to, i walked over there and asked what was the problem, he pulled me away an to the side. i glanced over at her and saw she was giving me a nasty look, i asked him, now if this is your "friend" why is she giving me that dirty look, he said because i interrupted their conversation, i told him there and then you need to tell me what is going on. We walked to the side of the building and as i was telling him go and get her and in the presence of both of you tell me what is going on, i saw her and her female companion walking towards us. 
She came up to me and asked "are you and him in a relationship?" I replied "yes for the past four years", she then said " Vin and I have been in a relationship for the past four years as well, we have a sexual and emotional relationship" my heart was shattered at that very moment, i felt played, i felt embarrassed,  my stomach was churning, i could process what she told me at that moment. i somehow remained calm while she ranted and rave throwing drinks in his face and the whole nine. 
This was a married woman, who was apparently having marital issues. My mind went far out; what if he has been having unprotected sex with her, what if she has been having unprotected sex with her husband, who her husband is having sex with. At this point i was sick in full, i couldnt believe my entire relationship was a folly. I felt broken in two but i was so calm one would never imagine this was what i was going through. I asked him why? why do this to me? Of all the pain i have been through you just had to cause me further pain, he couldnt answer my questions. To this day i am yet to recieve a real reason why because there where moment in our relations that he could have stayed with her. i asked him why come back?? he couldnt  answer that either. 
This is a lesson FOLLOW YOUR INSTINCT NOT EVERYTHING IN A RELATIONSHIP SHOULD BE SWEPT UNDER THE CARPET, I DID IT MANY TIMES AND I GOT BURNT BADLY. 

MY HEART ACHES AND TODAY WHEN I THINK OF THIS MOMENT IN MY LIFE I FEEL SICK TO MY STOMACH TO THINK THE PERSON YOU LOVE AND CHERISH WOULD DO THIS TO YOU IN RETURN.
theworldisacycle02 theworldisacycle02
22-25
May 9, 2012