Lonely, but afraid to get out of non-marriage?

i am allowing fear to rule my life right now, and i need to take charge, but i'm having extreme anxiety about making the big move to divorce. my husband moved out over 1.5 years ago (1200 miles away). he is a person who has fabricated most of his life, which i discovered after 4 years of marriage. i didn't confront him with all the lies because i was advised that it would be damaging to him and possibly to me. around the time that i uncovered all the lies, he was diagnosed as bipolar and quickly moved away. he still calls several times/day and still offers financial support. i don't know if i'm afraid because i don't want any more failure or because my faith is just not strong enough to believe that life will be ok for my 14 year old son and me....(keep in mind, i have had -0- romantic involvement with this man for over 2 years). i am a fitness instructor, smart, and capable, but for some reason--i'm stuck!! i'm very embarred that i've allowed this legal "arrangement" to continue on for such a long time while my life is on hold. i want what is best for my son and have economic as well as social concerns for him. i realize this is all ridiculous, and don't know why i become a nervous wreck every time i start to take action on this. any input (preferrably from people with wisdom and kindness) would be appreciated. maybe there is a word of profound meaning that could be shared with me.