Why Was This All Necessary?

I sit here and wonder WHY was this all necessary? What was the reason that I had to go through all of this heartache and pain ?  Why did I have to suffer from him hurting me so much? ....the name calling, the lies he told and believed for a very long time, the worry of WHERE he was and the final break-up of my marriage and family. It seems that I can look around and see so many couples who make it through, and some that don't, and then there's just me. I wondered for a very long time if I had anything to do with his cheating.....but I know that I didn't.  I was always there for him, and sometimes think that I gave him way too much of myself.  I see him, right now, with his other woman, and he is also cheating on her...go figure.  That man just can't seem to find happiness within himself. Why did he even want to marry me or have a family with me if he wasn't happy?  Did he honestly try to be faithful?  So many questions, and you know what?  none of them will ever be answered, I know that already.....my question is WHY did I have to go through such pain?  Maybe one day I will find the answer.