Needing time and space is a type of marital separation that doesn't necessarily mean the end of a marriage. Time away can help each person gain new perspective and opportunity for self-exploration. However, it needs to be clearly defined as to what "time away" means so that the goals are the same. Parameters need to be set with the intention of maintaining the integrity of the marital vows. For example, if the intent is to gain perspective and stay together, fidelity must be agreed upon jointly.
On the other hand, if "time and space" for your husband is a precursor to formal separation and divorce, then that is a reality that you will eventually have to accept. It is imperative that he communicate his intentions to you to not give you mixed messages.