Second, stop asking your child about "Ella", not only will it confuse him but it will not make you feel any better and just drive you crazy.
I know that it is very fresh and very painful right now, but I would strongly suggest getting your hands on a copy of DB and try to do some GALing. You are so very focused on what he is doing and where he is that you are not living a life but instead clinging to the edge of a very tall cliff.
At the times that your H is with your S you need to leave the apartment and go out yourself, get together with friends and do something, not just meet and talk but a physical activity that takes concentration to do.
Don't bring up the R in talks, right now he is a brick wall, so only contact him about your S and only if issues come up.
Do things for you, find things that you enjoy and take time to improve yourself. People are attracted to people that are happy with who and what they are and right now you are misserable and unhappy because you lost yourself in a combination of people (you, H, S) taking your identity as W and M and losing who you are deep inside.
Your son will benefit from a more relaxed mother when he comes home and you will benefit from finding yourself and your strengths again... maybe even a "Mommy and me" excercie class or swim calss so that you can help your son reach goals that the two of you can celebrate and when he is with your H a belly dancing class for you. It is fun, great excercise and builds confidence as well as gives you something to practice and concentrate on and if you want a real belly laugh then you can dance with your S... there is nothing like the sight of a 2 yr old dancing to bring light to the darkest heart.
But first... breath... you can do this, the worst thing that can happen is that you disciver that you are stronger than you thought... the best thing that can happen is that your H notices that you have found your confidence and strength and will be attracted once again to the girl he once knew but lost in the morass of responsibility.
M- 11 y H- 40 Me- 41 D (1st M) 19 S (1st M) 17 First EA (w/OOW)discovered 2000 Third EA (w/OOW & phone) discovered 02/06 SSM (total) 3 1/2 years
