How to leave

I've been in my relationship for 2 years. We live together. I have felt unsure for a long time but continued the relationship because I am mentally ill and don't always see things accurately so I just tell myself I'm overreacting or scared of commitment or abandonment. My partner bought a house (independently) and we are scheduled to move there in 2 weeks. I have been struggling for months with multiple things but there is no cheating or blatant abuse, I feel sick at the thought of leaving but I'm unhappy. I just feel like even though I love her its not the right relationship for either of us. We both keep trying but I'm so tired. I find myself wishing she would end it, because I'm too much of a coward to do so. But then when I think of being apart I feel great relief mixed with huge heartache because we've been inseparable for 2 years and she is a big part of my identity now. I just don't know how to move forward. I don't feel ready to move into this house, but every time I bring up doubts of fears I end up apologizing and we continue on another day and I feel worse every day. Our relationship isn't bad. But the things that are off just feel important. If we didn't live together I would have asked to go on a break a while ago but its just not an option. I feel like me ending it is not an option. Id rather be unhappy forever than hurt someone I care about. Just exhausted from the constant guilt for months and weeks.