There’s a common misunderstanding that it may be a good idea to get a legal separation and a divorce.
An annulment ends a marriage by declaring it was never valid. The grounds for getting one are limited.
If you are separating it’s often wise to work out a separation agreement, whether or not you are married.
You can get a legal separation rather than a divorce. In practice, they are uncommon. They don’t end the marriage.
What is the significance of the “date of separation” in a divorce?