Is it cheating if you have filed for divorce?
If you are having sex with someone else before you are divorced, you may technically be committing adultery. If you live in a state that still recognizes fault in divorce, then your "adultery" may affect your ability to receive spousal support. It may also reduce the amount of spousal support you receive.
Is dating before divorce adultery?
Technically speaking, going on dates is not an act of adultery. Family lawyers will tell you that adultery is only committed when sexual contact is made between a married individual and someone who is not their spouse.
Will having a new partner affect my divorce?
While this won't affect your financial settlement in any way it could have other repercussions. For example it's unlikely that your new partner will welcome the fact that he or she could be named in court documents. In addition, including adultery as the ground for divorce rarely if ever makes a divorce more amicable.