I vote for the last idea. Sounds like, from what you have described, that she would already know you are there for her at this time. At most I would tell her that and leave it at that. Do you really want to be her friend after she ends your marriage? It doesn't sound like you do in other posts so why tell her that now? Just be "aloof but available" (not sure who said that but I like it). As far as her worrying about you talking bad about her, I think that one just needs to be demonstrated by your actions and don't worry about what she is thinking or not thinking.
CB
Me; 42, W; 43 M; 16 yrs S12, D9
3/13 - "I want to move to XYZ City (four hours away) and it might be without you, not sure" 5/13 - "Not sure I meant that"
