Hi suesuekp. Welcome to the forum.
Competing with her for our husband's time and attention has not worked for you. The competition continues to end in a tie. Time to try something else. Since fighting each other has failed repeatedly, why not try working together?
It looks to me like the three of you are already locked in a V, like it or not. You've already tried to just terminate the relationships and haven't been able to, so it seems like the next step is to find out how to make it work.
Each of you individually needs to take the time to figure out what your authentic needs and desires are, and what obstacles are really standing in the way. This will take however long it takes and will involve a lot of work on yourselves. Professional assistance is often helpful. The three of you together need to understand the needs and desires of the others and come to an agreement to see that everyone's needs are met. Yes, even hers, if you want her to join the effort to see that your needs are met.
Easier said than done, I know. But easier done than you might think, and certainly easier than continuing to torture yourselves and one another.
Good luck to you all on the journey ahead.