What Am I To Do About It Now

In my spiritual walk - I often feel that I am one mistake away from eternal damnation. I fear repeating the mistakes I have already made because I fear not being forgiven for them by God. Is this silly of me? I do try, especially now, to approach each day with the intention of making a measurable effort at avoiding the sins and mistakes of my past. And I know that perfection is unattainable. Yet I feel there is this line I am in danger of crossing from which there is no returning in the eyes of God. How many times will He tolerate my falling down? At times its almost intentional. Maybe not intentional - but I am old enough to know what I am doing. To recognize the signs and behavior. And inevitably there will be consequences. And its those consequences that I am afraid of. I'm afraid I'll find myself in a situation where I am "unforgiveable". And then where would I be? I don't think I could bear that.