I'm sorry you are experiencing this. Im sure it is playing hell on your self worth making you feel like you have been discarded. I know its very difficult to convince yourseof of whether what they are doing is right or wrong. If it's just right for them? If it has anything to do with us? Etc. Sometimes I look at the dynamic of relationships. Guy meets Girl. Guy and Girl love each other. Societal influences and willigness to marry. Decide to get married. Have a few kids, ten years go by. Feelings change. Struggles come up, unresolved issues persist, boundaries get crossed....you know life...People start to question how the relationship is benefiting them. They want to start pursuing Independence liberty and freedom, I no longer want to be tied down or at least to that person. I think some people eventually get tired feeling obligated kids spouses family members, Etc. They lose themselves in their identity. I know from an outside perspective it seems like they're putting all their newfound friends first and you last, when you used to come first in their lives. That you are somewhat missing out. That their happiness is coming at the expense of leaving you. I know it hurts, and I know they can't see it. But AT THIS TIME They have to do what they think is right for them. Whether you know its right or wrong whatever it is they are doing. They did what they thought was right when they got married, they thought what they did was right when they hunkered down and probably took on more responsibility then they could handle and lost themselves and their identity in the process, and wanted freedom from that. If someone lets you go, its [censored], it hurts, its unraveling, uncoupling, and all these other helpless, lonely feelings that are attached to you, your identity, and worth. Iblmiw it feels like betrayal. But it doesn't have to be. Granted we don't have control over choices other people make, but we do have control over ourselves, and the meaning we assign to tjings, how we think about things, and how we respond to them. Try to be happy for her. I know it feels like they are making out, and you are losing. Try to be happy for them. Even if it isn't what you want. Because holding onto someone that doesn't want us, and us focusing on their happiness keeps us from growing. People stay because they want to stay and leave because they want to leave.
What do you think you can do right now to keep the focus on you, get comfortable with you again, and do what is right for you RIGHT NOW? What can you do/plan/learn from this to get you moving in the right direction of personal fulfilment? Right now you have to figure out how you want to be and what direction it is going to take. Because obviously the other person isn't going to share it with you. So you do have a choice. Maybe not the best of current curcumstances, but you do have a choice.
Hope this helps. There will be something good to come out of all of this. It may not be right away, next month, or next year, but we will all eventually get there.