I think it is okay to reach out to W and let her know that the cousin had been in touch with you regarding the M. You would want to do the following:
-touch base with W and ask how she's doing -ask her if she is willing to talk -preface by saying that you stayed away out of respect for her -you are taking a risk here -feeling scared here and say that you can only imagine she probably scared too -seek a confirmation that W did indeed say such words to cousin -state firmly and calmly that you want her and the M -it seems that two people are in a world of pain and not knowing how to reach out to one another -hope to begin slowly build bridge somehow -this will require patience and understanding from the pair of you -then nicely end the call with an appreciation for her willingness to talk
Listen and validate.
Say you have had some time to do some reflection and introspection.
I think you are more than ready to handle this talk. What do you think?