[...] I just don;t know what to do [...]
Could you experiencing 'the F.O.G'?
[...] my responses aren't helping either of us. [...]
Could be... writing and reading here is not a bad start, I suppose...
[...] It is truly exhausting.[...]
Sounds like more 'F.O.G' to me...
[...] Most people [...] tell me to just walk away [...]
Sounds like you agree...
[...] I don't want to be another person who has just casts him aside [...]
I wonder how you made the connection - "I'm wπalking away - therefore I'm casting him aside".
How about:
"
[...]the intense emotional abuse is very damaging for me.[...]
... I do not want to live that way and there is no good reason why I should.
Since boundaries are not being respected, walking away might be the only way to protect myself."
Reconsider your "O" = obligation.
Make sure your actions aren't driven by "F" = fear.