Life takes hold and being a mum too there's so much to do. It's good that you recognise what you could do and even changes that would benefit you. This is still very new to me too but I've read a lot about validating and if/when H initiates any R talks with you then it seems to be a case of also acknowledging that we as the LBS would also like a more fulfilling R and acknowledging what we could do to help this process.
Mia I really wouldn't focus on the OW too much. I know it's the most hurtful part, I'm in the same sitch too. H is BOUND to be really in to her. He's got the same way of thinking currently as a teenager. It's like that first crush you have as a teen, you think they're the best thing since sliced bread, your heart pounds and your stomach flips at their name let alone the sight of them. H once felt this for you, if he didn't you wouldn't have got married. H doesn't know the OW and she doesn't know him. Whilst I don't believe in pulling people apart I know that I have enough strength of character and values not to get involved in a R with a MM. The OW is likely to be missing something herself, she's looked at the life you and H had and wanted that. You should actually take it as a compliment. What hasn't dawned however and may it will, maybe it won't and who knows how long it'll take, is that the reason you and H had the life you did was because you were part of it. Their R will never be like yours because she's not you.
HB says that the man the OW has now is not your H, your H would not treat people as he is. She has a lesser version of him, one who may be convincing in the show he's putting on to impress her but would you want to be involved with someone going through D who's going to have tears, tantrums and everything inbetween? I know at some point I'd run for the hills!
I'd tell your SIL that you're not interested in hearing about H, the OW or what they're doing. It's only going to consume you and you don't need that weight on your shoulders.
If you are really focused on the OW Google some articles by people who were the OW. I've read a few and the message seems to be it's not all a bed of roses! Xx
Me: 38 H: 40 (39 @ BD) BD: August 2015 T: 22 years M: 15 years D: 18 years (17 @ BD)