Whatever has happened previously Garlic, you are now showing a maturity that sadly your husband doesn't appear to be. I hope I'm wrong, but I have a sense of his "needing space" to actually mean that he just wants to sample the single life again, before finally confirming your marriage is over. This is fine provided he is also, like you, using this time to truly reflect on how you have both behaved in the marriage...not just you. For this reason, it would be best if you encourage him to give his thoughts first, before you jump in with all the things you believe that you have done wrong. Don't give him a stick to beat you with, until you actually know what you're being accused of. Once you feel that you are both singing from the same hymn sheet, then total honesty from both of you is the only way forward.
Please rein in your innate sense of immediacy, for your own sake. This is absolutely not a criticism, but it can totally overwhelm someone of a quieter nature, and cause them to withdraw.