Yes, that was insensitive of him.. unless he doesnt know the circumstances you split? But I agree, you did the right thing, you were polite and then left. You must have handled it well.. to inspire her to send the text by apology, she must care how the encounter affected you, which is something hey.
And yes.. I know those feelings of "if only I had seen the light sooner" - you have learnt your lessona and been altered by this experience, opened up, more capable of truly loving someone and yes that is so valuable...but what a shame you had to lose something so precious in order to learn those hard lessons.
Its horrible, the reality of the OP.. and you have it in your face, as you have to make arrangements about your son and you cant really avoid that. You are coping with it, becuase you DO love your W, thats plain to see. She is a lucky woman that you remain so loyal and committed to her, but I guess she wont be able to 'see' that. Be proud of yourself hey.