Hi,
I think that at least partially your barriers to accepting love are related to your childhood and your early relationships. Understanding the genesis of your patterns of behavior would not only help you to manage yourself better but also may ease your feelings of guilt about the effects on your loved ones that your behavior produced in the past. I do not know you but I am not sure if you could have been different. However, in the present moment you can improve. But perhaps you will have to be mindful of all the stuff that was passed onto you by your parents and other SOs during your childhood, and of all the stuff that happened to you in the past and made you in the way you are. In my opinion, we are not that "free". We are highly conditioned by events and people that were important to us when we were children. We need to go through a long path of self discovery to disentangle such influence. For some of us the process need decades before we see good results. I know we have made wrong decisions and suffer people unnecessarely. But also I know that we have had little margin to manuever.
Sorry if my words are confusing or not helpful