I am concerned about your message as you appear very conflicted. You appear uncertain as to which man you want to a relationship with, however I am not sure you want to pursue a relationship with either man. You indicated you did not choose either man, however your partner left the home and your ex moved another woman and her children into his home. Is it possible you have difficulty being alone, without a partner? Some people define themselves by their relationships, i.e., being part of a couple. As an adult we can be alone (without a partner), not lonely and be in a relationship and feel consumed with loneliness. The difference is if we are not fully satisfied and comfortable with ourselves then the likelihood of being satisfied and comfortable with someone else is not possible. I encourage you to explore what makes you happy, what is fulfilling to you before attempting to engage in another relationship. After all, out of all the parties in this triangle, shouldn't you be the one worth fighting for? Don't you deserve to be happy? Happiness comes from first being happy with yourself. I would also encourage you to seek individual counseling to manage what I perceive to be depressive symptoms and low self-esteem.