Divorce is incredibly state-specific, so before you get too far in the planning process, it's a good idea to check out laws in your state regarding divorce, separation, property distribution, support, and custody. For example, in some states, you have to actually file to begin your period of legal separation. In other states, you don't even have to be married for your relationship to qualify as a "common law" marriage. (That's not the case in Virginia; we don't recognize common law marriage.)
In Virginia, you don't have to file for separation. You are separated when at least one of you forms the intent to leave the marriage and remain permanently separated from that point on. "Separation" doesn't necessarily mean physical separation, but it does mean that you must stop cohabitating, or living together as husband and wife. In many cases, you can prove to the judge that you've been separated, even if you and your husband choose to live in the same home. It is important that you make a commitment, at the time that you separate, to actually live separately. If you're wondering whether you can do something, ask yourself, "would I be doing that for him or with him if I lived in my own place?" If you wouldn't, then it's probably a good idea to avoid doing it once you're separated.
Remember that just because you're separated doesn't mean you are any less married. In Virginia, you're married until you're divorced. If you have minor children, you must be separated for a year before you can get divorced (or six months with no minor children). Separated is the same as married, at least for the purposes of adultery. In Virginia, adultery is a misdemeanor offense. It is unlikely that you would be prosecuted for committing adultery, but it could affect other entitlements you might otherwise have–so be very careful!
If you've committed adultery, you'll be barred from asking for spousal support unless you can prove that some sort of "manifest injustice" would occur. (Trust me, this is a hard thing to prove.) Likewise, if your husband has committed adultery, he will be barred from asking you for spousal support. Of course, I am assuming that all the other factors support an award of spousal support, because it is not always guaranteed.
It's definitely important to know how your particular state operates before you get too far into your planning. The choices you make now can affect your entitlements later, so it definitely pays to be informed. If you live in Virginia, request a free copy of one of our books, "What Every Virginia Woman Should Know About Divorce," What Every Virginia Military Wife Should Know About Divorce," or "The Woman's Custody Survival Guide," to get started! See the links below.