How can i help being jelous on my sons girlfriend.?

Despite what others think, this is completely normal. Yes, normal. He is your son. He has been your son for 20 yrs. You should know him better than anyone. All mothers feel jealous when their kids find someone. You're going to feel like this girl is going to take him away and you'll hardly see him. You're going to think there is no way her care can compare to yours of him. Now, even though you may be feeling and thinking like this, you have to bite your tongue. If you don't, you'll risk losing him completely. Now its okay to tell him you feel like you'll be losing him, when you actually find out they are engaged. This girl may just be a friend, not a girl friend. Either way you have to be a responsible adult and let him live his life. You don't want him lonely after you're gone, do you? Plus he will never learn to love and trust a girl if he doesn't try. :)