Joshua, I am so sorry for what you have been through. I can relate so much to it and can empathize completely. It must be a tough time and it has gone on for a while it sounds like. So please, first take some deep breaths and try to slow down and relax a bit. You've probably been running at this at 100 mph since it all started.
First, do not blame MC or the MC for their methods. MC NEVER works with a spouse that is not committed to it. Even if the MC had given you actions and homework, more than likely she would have refused to do it. Her heart wasn't in it. Your MC probably detected very early on that she had 1 and 1/2 fee out of the door and realized that "actionable steps" were futile. Most LBSs immediately jump to MC to try to save the marriage, but the truth is that once the D bomb is dropped, it is too late for MC.
I also detect a bit of Nice Guy, I don't deserve this thinking. I would recommend reading No More Mr. Nice Guy. NGS is not a healthy way to approach relationships and other people. You might find the book useful for your go forward.
As far as what you do, well, the question I have is how patient do you want to be? You've waited over a year so far, how long are you willing to wait? Likely she is dating and seeing other people, probably the AP. The fact that you keep reaching out tells her "I can get Joshua back any time I want to." Plan B is not a fun thing to be. So my recommendation is to remove yourself as Plan B, that starts by NOT contacting her anymore.
Then you go out a live an awesome life. That is why the DBing advice is to GAL. GAL is your top priority right now. You do not do it to try to get her back, or to show her, you just go live your awesome life. If she takes note through friends and family, great. If not, great to that too! Then you keep working on you. Become the best version of yourself that you can. You tried MC. I would suggest instead IC. Get a good IC and go to work on becoming the best Joshua you can be! And then you have to work on emotional detachment. Detaching emotionally from what she does or doesn't do, what she says or doesn't say is the goal here. The goal is that if she never reaches out to you again, great. If she does, that is ok too, but you will remain emotionally even through all of it!
Finally, one thing that helped me in my sitch was to set a drop dead date. A date that if she didn't recommit back to the marriage, and hadn't filed for D herself, then I would go file for D and move forward with my life! I highly suggest that for you. I set it 1 year past BD, but your situation is a bit different. How much longer are you willing to wait? A month? 6 months? A year? Figure that out, set a drop dead date, and when that date come you go file for D.
One red flag I do is is that she was awfully young when she was in a serious committed relationship. If my math is right she was 20 when you started dating? 22-23 when you got married. That is very young especially in today's world. She has a lot of maturing to do, and she may wake up one day and realize that she walked away from the best dude she ever knew. Or she may just move on and never look back. Life is short though, and I would highly suggest you do not wait for her for too long. I am 53. 34-53 flew by! So decide how long you are willing to wait, then realize you did all you could do and move forward with your life.
Finally, understand that you will be ok. We have a sticky thread here entitled, You Will Not Die. Please read it. There is life even after D.
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018