I understand what you are both saying about how I am wording things and how it can be misinterpreted, I guess I just don't know how to word it better.
No, if I were single I wouldn't want the responsibility of fixing someone's marriage. I'm not sure I would know how to join a couple and make everything better. My husband and I have a beautiful life and marriage and if we continued our life monogamously we wouldn't have any problems. It is because we have so much love for each other that we want to share it with someone else.
I say "add to" and "bring in" only because we already have an existing relationship. It's not as though we are all single and starting something together, though we do want to form an entirely new relationship together. We aren't looking to "add her" to what we already have, we want to create something new. So I probably should have said something more like that, but I didn't think or see how the words I was using could be viewed in a negative way like that.
I have been doing a lot of reading on and off this site and I know there is a lot to learn. That is why we don't want to rush things. We want to learn the best and most fair way of doing things so that everyone benefits from this relationship, not just my husband and I. We don't want to make the same mistakes that a lot of couples like us make. We want a lifetime relationship with someone. So we still have a long way to go, but we are trying.