First off, if you are having troubles with your current relationship decide if the relationship has a future. If it doesn't end it. There is no use being in a relationship that stresses you and doesn't really have a future. Being single isn't all that bad with good friends.
It sounds like your ex has feelings for you still, but if they are strong or not is something that he might not even know. That he contacted you while in a relationship tells that either he just missed you as a friend, or that his current relationship has times he wishes he wasn't in it. His offer to you to come around if you needed someone to talk with or watch a movie with ... could just be concern for you or his wanting to see you to figure out what feelings he has. It is a non-commit way of checking things out.
Since you never stopped loving him, this could be a heart-breaker for you. But, you might want to take him up on seeing a movie. See how things go in person. But, don't let things go too far unless both of you end current relationships. Not only is that the right thing to do, but it shows commitment and ethics for both of you.
Good luck!
