I have just started exposing my WW today and would like some advice on how to handle what coming?

I expect plenty of anger, rage, and shame. I have already exposed at work although she probably won't hear for a day or so. I plan on exposing to her IL's tonight and maybe her siblings as well.

She will deny everything of course, so how do I prove it?

You hopefully won't have to. Simply tell those that you expose to that you HAVE the proof. Tell them that you're working to save your marriage, and that you're asking for their assistance in helping you do so. That includes speaking with your WS and advising her on things that need to happen to save your marriage (NC, communication, etc...).

Your wife will be FURIOUS...but simply and honestly tell her why you did what you did, and don't respond in anger. Tell her that you're fighting to save your marriage, and that affairs simply can't stand the light of day...which is why you're trying to make sure that everyone who knows her can give her the support she needs to heal and to rebuild the marriage you two have shared.

She won't like it, she'll call you names, etc...but don't respond. Stick to the standard response, and tell her that you love her and won't just give up on her. She's worth the fight for her.

Again, it won't sink in now, but it SHOULD sink in later!