Like you I read posts for a few months and found such comfort and hope. Your post has lots of similarities to my position. My dil doesn't want a relationship with me and no matter who upsets her from our side of the family all the hate and rudeness comes down on me. I feel I will never say or do the right things as far as she is concerned. It has made me ill.
The best piece of advice I was given on here was to back off for a while. It's been difficult but I feel better than I did and ds has been in contact (without the usual dramas) which has really boosted me.
I think the fact you haven't been invited to your ds wedding is absolutely awful and you have every right to be confused/angry/hurt and your ds must realize this. The thing is though as bamboo2 said he will be in a tough spot trying to keep everyone happy. I nearly lost my ds because I " said too much". It's not right what is happening to you and your family but if you want him in your life you will have to accept a different kind of relationship. This is all so hard I know but surely you deserve peace and a happy life after bringing up your children.
The other advice that helped me was to fill my time with things that made me happy and to spend time with people who appreciated me. The ladies on here have wonderful advice. I'm not so good with words but I do know how upsetting this all is. Keep as calm as you can SH and don't let FDIL bring you down. You will always be ds mother no matter what Take care xx