You wanted to work on your marriage and dating other people would have only further complicated things. In fact she could have used your doing that as a stick to beat you with too. Your heart is in the right place where you want to work towards getting your family back in tact "if" you can.

Could she be using you? Possibly, but none of the members here KNOW her and all we do know is what you have shared. I agree with Bill3 in that you should seek a marriage counselor asap. Does the T you are seeing know anyone he could recommend?