Don't take the "insecure" bait! I hate it when common sense caution and justified possessiveness is translated into insecurity! You should be concerned about his many women friends and especially about the one who had admitted to liking him.
I agree with the poster that said she aint never had a hetero male friend who wouldn't hit it under some circumstance. Ask him if they've ever been intimate...Every chick a guy has labled "crazy" usually has a story behind it about how she got that way, and most of it is about the emotional rollarcoaster the guy has had them on (ie leading them on, having sex then saying they're not "ready" for a relationship). And just like you guys flirted off and on for years its possible that he did that same thing with her...just without the next step of a relationship. And we know how we can think as women..."If I wait around and be a good supportive friend he will eventually see that I'm the one for him and be with me."
If I had a guy friend and one of us was in a relationship and he declared his feelings for me I would immediately stop being friends with him! Nope...I will not entertain your unfaithfulness to your SO nor would I put my man in a position to be unconsciously competing for me. That is completely egotistical.
He may be a part of the 5% who have completely good intentions but weather or not he is, you really need to make your feelings known and check that in the beginning.
Though I would want to go to the funeral, I don't think its a good idea because you already know she has feelings for him and seeing him with a girlfriend at her dads funeral could be overtaxing to her emotionally. Just because she backed down doesn't mean her feelings disappeared quickly. No need to make a statement in her time of loss.