Unless you are a very detailed person, I would recommend a lawyer. The issues are these. It has to be very simple, very direct, and all the dates and time lines must match. You want the information to be easy to read and not cause any 'red flags' or issues to pop up. An example is when they put all this information into the computer; they will cross check dates and times. Were you in china during this day, and did you say in another place you had web cam data. While all questions might have an easy answer, what you want to avoid is having any questions by the processing people. Any request for information to answer small questions will delay the process. The affidavit that Maxx referred to is very crucial. Along with that you will need to send copies of all legal documents. Birth records, legal residence, divorce papers, for both parties. They will match these dates with the affidavit and see if any questions arise. Again the answers may be very simple, but you do not want any delays so getting it right the first time is important. Once they start to pick apart an application, there will be delay after delay. Can the visa be done without a lawyer? We have seen that it is possible. But if there are any issues at all that may cause alarms to cause delay, I would recommend using a lawyer to get the quickest action on the visa.
Of course this is just my humble opinion and the reason I spent the bucks for the lawyer.