He engages with you because YOU respond.
Alcoholics love all the drama, gives them an excuse/reason to continue on their path of self destruction.
I promise, if you STOP responding, he will stop texting/phoning. It's really that simple. ( Might take a week or two, but he will lose interest and will find himself a new hostage)
You don't have to respond, but why do you think you need to be worthy of his affection?
I see you struggling with rejection, but as far as being worthy, I think you have it backwards, he is the one that is NOT worthy of your precious life and time.
You get to decide, how long you want to dance this toxic, toxic, dance.