You are single but unavailable for the time being.
You look at what the problems were in your relationship, look at your part in those problems, decide if you want to change your behavior, the act accordingly. If there are things you want to change but don't know how then you seek guidance from a counselor or therapist.
Keep a basic level of contact, be friendly, let him know what you are doing, "Hey, how's it going, I'm doing okay but had a rough day yesterday. I found a really good therapist and she is helping with issue xyz". If he really is interested in continuing the relationship he will be responsive to your communication and efforts at effecting change. If you feel that he has really pulled away or is uninterested you need to communicate that to him to gain an understanding of how he is feeling.
At some point in this process you may need to accept that the relationship is done, just make sure it is a clean break where you both understand that you, as a couple, aren't coming back together. At that point, if it comes, continue to make self improvements and move on with life.