Everyone has trouble with the 180. The good thing is if you mess up you just start right back up again.
I started off small. For instance I stopped calling my STBX while I was at work. Then I stopped talking to her completely unless it involved the kids or finances. We were still living together at the time so if she tried to start a conversation I would either ignore her, nod my head, or give very short answers like yes or no. If possible I would get up and go in another room or go do something.
The other important thing for me was starting to live my life again WITHOUT my WW in it. You want to take the focus off of your WS and put it back on YOU and what you want. This meant doing things I wanted to do. In the beginning it was tough since I had no idea what that was anymore so I made a list and put as much stuff on it as I could think of like work needed around the house, trips I wanted to take, things I wanted to do with the kids, basically a bucket list with big and small things on it so I had something to do from the list everyday for a long time. workign off the list gave me something to focus on other than my WW. I started going to the gym as much as possible, visited family on the weekends, or going to the movies to start living my life on my terms again. So make a list things, events, musems, hobbies, you want to do and start working on it.
The key for me was starting small. Pic one or 2 things off the 180 list and try that then build on it. Something as simple as nto making his plate at dinner anymore, no longer washing his clothes, not calling him at work, not saying good morning or good night can be a starting point. You know yourself best. Just stop donig the small things and they eventually turn into big things.
If you have children, they are 180 superchargers! All the time and energy you used to put in WS you now refocus on the kids. There is plenty of free stuff to do with kids. Museums, the park, day trip to another town, you name it. Focus on them and you take the focus off WS. I wish you the best keep at it. If you fall then get right back up and start again.