You are neither unworthy nor a disappointment. This is where you need to do selftalk. It is the abusers voices speaking to you in your mind right now. So you need to tell yourself aloud the opposite of what they are saying - do it each time you hear the abusers voices.

In this case .. you would say.

"I am worthy of love"
"I am worthy of support"
"I am useful"
"I am not a disappointment"

Say those things (the opposite of whatever you are hearing) at least 10 times ... after a doing that for some time, it will erase the mean things that were told you.