Never let yourself be an option for somebody else. Relationships should be built through trust and faith regardless of your beliefs.
I applaud that you have loved a person truly and openly that you gave everything that you can. But, know that there are better things for you out there and the only person holding you back on attaining those positive things is yourself.
I have this friend who recently broke up with his girlfriend but after three months of their break-up, she wanted him back. The answer was so obvious when he asked me what he should do. I told him, you have lived without her for the past three months and you've been trying your best to get yourself back together so that you can move forward with your life. Do not go back to that person. Harsh as it may sound, there is a reason why they are called an "ex". They are those people who came to your life but the relationship didn't work out because there were a lot of things that lacked in your attachment. Do not call it a mistake but rather a lesson that you have to be thankful for because through our lives, we would get to know ourselves better through experiences. As they say, there is always a light at the end of the tunnel. So try your best to look at the bright side of things and with faith and belief in yourself, you will be surprised of the better person you will become :]