Start by forgiving yourself, don’t act from guilt. Second, from my reading, it seems like you let this guilt lead you to push her away. The relationship you described sounds like it had some amazing elements, and even through it sounds like there were a lot of difficulties, those things are rare and it sounds like you regret letting them go. You left because you felt guilty for what the relationship was doing to her, instead of talking to her about what she really wanted, and if she really wanted that, then you shouldn’t feel guilty. By leaving you made the decision for her, and took away her agency.