I had a really hard time reading your post because of missing letters, shortened words, and incorrect letters....it would be much easier to read if you just typed full words! Just a tip for getting more people to read, understand, and feel confident in replying to your posts.
But, assuming I correctly got the point - you feel bad for breaking up your boyfriend's old relationship, despite him telling you that he's happy to be with you.
All I can say is that you have to weigh whether you think he's telling the truth and make a choice of whether you believe him. If you believe he's being honest and is really happy to be with you over the other girl, then just stop thinking about her, because if he really wanted her, he would be with her. If you don't believe him then make the choice to end things before you get hurt. Don't stay if you're constantly anguishing about this. It's not worth it and you'll just end up making things difficult for him if you keep asking him again and again for reassurance.
Good luck.