I won't try and claim I know a whole lot about swinging or open relationships since we've only been swinging for less than a year, but we have been together for a long time and I think I've got a decent handle on building and keeping a healthy relationship.
To me her online addiction is a symptom of her being bored with her life, you mentioned some depression, she doesn't know what she wants (the shrugs) and is enthralled with her online game and the people she is meeting there. She is hiding within there to shelter herself from the monotony of her daily life. You can't force her out of that place, you can only control yourself and your own actions. I hesitate to get too personal, but if you're not comfortable answering just think about a few things to yourself: do you have many hobbies that get you out of the house? Are you physically active (playing sports, going to the gym etc.)? Do you go out a few nights with your friends on your own? Do you and your wife do anything together (hobbies, travel, trying new experiences other than having sex with others ?
When my relationship was at a point where this kind of thing was happening (although not to quite the same degree I'll admit) what got us past it, and brought us closer together, was me getting out and being active outside of the house. Spending time with friends, trying new activities, meeting new people (just friends, not sex), picking up old hobbies and generally leading an exciting life. Doing things that were fun and exciting to me. After a little while of seeing me having such a great time my wife poked her head out of her stupor a bit and rather than just waiting for her to tell me what she wanted to do, or ask her how she felt I lead her into my exciting life. One day when she seemed to be in less of a funk I told her that she and I were heading out for the night. She jumped at the chance for a night out together and I took her out for a date just the two of us. After that I started to get her out doing activities that we'd used to do together and things that I know she loves to do. Trying new things together, doing activities we both loved and sometimes activities only one of us loved (I so love to see her super excited and am happy to sit through the opera to see that).
What happened with us is that we'd gotten bogged down into a monotonous life together. We had stopped doing the things we loved to do and forgot what it was like to have an exciting relationship. I have made a point to ensure that we don't slip back to that. It doesn't mean that every night or every week we have to be doing crazy new things, but we consistently are doing something we find fun and we try new things together or do old things that we love whenever we can. Focusing on that has meant we haven't slipped back again and we both have been happy and get closer all the time.
My advice, take it for what it is (not trying to say I know all your problems lol, it just seems a lot similar to your situation).
Take care and good luck with everything!