I don't think any relationship is a waste of time. There is always something to be learned. Dave and I have both had long term relationships before we met and we consciously decided there was stuff we weren't going to bring with us into our relationship. We talk about what we aren't gonna do this time around married to each other.
What do you want to leave behind as you move into a healthy relationship? Remember that baggage is heavy, so why not lighten the load and make something fabulous together!