believing in things unseen

eventhough I believe in God and all he is capable of doing I cant help but to wonder why I allow my past to spill over into the present? is my past tied with my future and future is tied with my past? I hate feeling like I am not "saved enough" or perfect enough. Like how can God love me with all I have done. I get that we all have sins and we all make mistakes, but happens when you feel like you have made too many mistakes to come back? sometimes when I look at girls that all about God and would never and have never done a bad thing in their life, I think see those poeple deserve to have a great life. They have always followed God's voice. I know for me sometimes when I heard his voice I kept doing what I wanted and let me tell you it led to straight destruction. I sit back and think I know he has let my past go but I havent. I feel like that girl who takes back her cheating boyfriend but I never really forgive him, and everytime I see him I see him cheating. well that is how I feel about myself. How can God love someone like me. I am a saint with a sinners past. I want to be able to feel like I am worthy to be in the same present as these people who have never done a bad thing i their life...How do I???,,,,,