What I personally feel is that you both need to take a step back and prayerfully ask God about your relationship with each other. Firstly, if you feel you cannot live without this man, your focus is way off. God is the only one that we truly cannot live without. People fail. It's what we do, as you yourself have attested to, so to put all your existence into man is setting yourself up for a miserable life.
Secondly, there is healing, both of yourself and your relationship, but the underlying issue will remain unless you deal with it. What brought you to cheat on this man you can't live without? Have you and this man been intimate? Are you living together? I highly recommend that you both decide to abstain until you are married, be it to each other or not, but that you eliminate any sexual contact (if you're having it) and you deal with the issues that allowed you to cheat in the first place.
Thirdly, as you take this break and work on your individual issues and your relationship issues, recommit and center your life on Christ or you will end up here again. Trust me, if Christ isn't everything to you, nothing, no fear or rule or law or love, will keep you from sinful choices and habits. You have to be fully committed to Christ, locked on Him, regardless of what is happening around you.
Be strong and seek Him. Everything else is noise.
