You are not being selfish. Your marriage ended 8 years ago. You have met another person who makes you happy. As long as he treats you and your sons well, I see no reason why you should not marry him. Your sons are old enough that no one should be expecting that your fiancé would be replacing their father. If your ex is making things up and trying to sour your relationship by turning your sons against you, it is probably because he is jealous that you are moving on. What you need to do now is sit your sons down and explain exactly why you would like to remarry. Make sure they understand that your marriage will not prevent you from taking care of them and it will not hurt your relationship with them. Explain why you would like to spend your life with someone and how being alone makes you feel. Leave your ex out of the discussion, and definitely don't put out any theories as to why he might be saying the things he is saying. Simply let them no now that their fears and concerns are valid, but that nothing has to change after you get married. If they are still against it, consider waiting long to actually get married, which is a good idea anyway. Make sure you really know this man before he joins your family.