Don't file out of anger. File when you are over the anger and when you have had enough time to think things over. Decisions made in anger are the ones we regret. Also, don't file for LS unless you are ready for D. And if you are ready for D file for D. Talk to a lawyer about what is appropriate in your situation. I inquired about LS and my lawyer told me it was better to just go for D.
One good thing for LS, and what he's doing... he won't need to feel so guilty! LS will make it easier for him to feel that what he's doing is okay. If you are LS, why not?
I know this is painful, and it's not going to change what he does. If he wants to do this, nothing will stop him. And anything you do to try and stop it will just make him angry and help him justify the decision. I personally think your best bet is to go "dark." Have no contact with him for awhile and work on you. If he contacts you be busy, you don't have time to talk, and FOCUS on YOU. Make YOU the type of woman he'd be stupid to leave.... and some other guy would be lucky to have. This won't happen overnight. You will go through a lot of pain, and it will be hard not to want to scream at him, or throw a cherry pie in his face, that's why it's important to go dark. You need to work through your anger and detach.
There is no arriving, ever. It is all a continual becoming.