Cant face the guilt of cheating. What do i do?

I know theres no real answer to this, its more advice Im after :(. Ive been with my boyfriend not far off a year. When we first started dating I was still sleeping with my ex who I was infatuated with all through my younger years although he was bad news. It wasnt regular, it was jus maybe a number of occasions, i would unconsciously go to his an we would have an I wouldnt feel a thing or any kind of guilt. Note that back then I was a pretty horrible an selfish girl. I only cared about myself an my boyfriend was nothing but lovely to me. I took him for granted. Then after couple of months of me going behind his back whenever i wanted some no strings with the ex I realised I could no longer do it, an I told my Ex to stay out of my life. Its been months an months since but my ex still texts me (to which i either do not reply or i reply with the "leave me alones" or "f**k offs") an I love my boyfriend more than anything in the world. (continues....)