the answer is one only you can know for sure .
ask yourself a couple questions to help make your decision .
is this man the kind of person , whether you are dating him or not , that you want to have around your son ? what is your sons relationship with his you and with his dad ? have you , or your ex had a relationship with anyone else that your son knows about ? do you want to hide from your son the fact that you are dating and there will be men in your life .
my own opinion is if the answer to the first question is no then he is not good enough for you . if it is yes then him being around your son would not be the problem , your sons reaction to you dating would be . if either you or your ex have had a relationship your son knew about he understands that both of you are going to have relationships . last but not least , honesty is the best policy . be honest with your son , tell him that you are dating and will continue to date , do not be ashamed , or apologetic about dating .
you are his mom , i am quite sure that you would never let anyone in your home , or around your son unless you felt like you could trust that person . your son is 15 . he does not need the same protection from you he did when he was 10 . he is more than capable of understanding that you and his dad are not together and that you do not intend on being alone the rest of your life .
whether a guy is just a friend , someone you just started dating , or someone you are getting serious with , as long you believe that the man is someone that is good enough to be in your sons life , you should never hesitate to have him around your son . all of us , not only your son , need to have as many good people in our life as we can .