What should I do? I have been aware of how toxic I am for dating someone who really loves me, but my heart still lingers for my ex. I don’t want to hurt him but I missed the attention so much that the only way I cope is to date someone else.
You don't love the person you're currently with, nor are you committed to them. They are committed to you, however, so you're currently using them. A decent person would free them from the farce, so they could have a chance of finding someone that would return their love.
Ignore the other commenters. Their advice is to mutually trap the two of you together in a life of misery and missed opportunities.
get to know the new person better and what they like, and ask for their attention if thats what you want, but if you can't love them then don't be with them
Have the new ones child, it wil connect you
tell ur current partner! dont stay with them because in this case you're just using them