Need to pass string with newline character from Unix shell script to sql query

I am using unix shell KSH scripting to do some table cleanup. I have a file "partner.txt" with 5000 line like this

>cat partner.txt

aaa0000
aaa0001
aaa0002
...
...
aaa5000

Using this file, I am supposed to clean few tables with matching, say agreements of the partners. So i am constructing a partner list string in the format that i can use in the sql statement with 'IN' clause (select * from tab where partner IN partner_list)

('aaa0000',
'aaa0001','aaa0002',...,'aaa0010',
'aaa0011','aaa0012',...,'aaa0020',
...
'aaa4990','aaa4991',...,'aaa5000')

I am assigning the string to partner_list variable like this.

export BO="("
export BC=")"
export BQ="('"
export QC="','"
export QB="')"
export  C=","
export CE=","'\n'
export QCE="',"'\n'"'"

partnerListLine=${BO}
while read partnerline;
do
    if [ `expr ${counter} % 10` -eq 0 ]
    then
        partnerListLine=${partnerListLine}${partnerline}${CE}

    elif [ ${counter} -lt ${numOfObsoletePartner} ]
    then
        partnerListLine=${partnerListLine}${partnerline}${C}
    fi 
    counter=`expr ${counter} + 1`
done < partner.txt
partnerListLine=${partnerListLine}${partnerline}${BC}

Then I am using this partner list to fetch my agreement list like

SQL_agreement='select distinct a.agreement from partner_agreement_map a where a.partner in ${partner_list} order by agreement asc;'

I needed the newline character in my partner list since i was using sqlplus and was encountering SP2-0027: Input is too long (> 2499 characters) I am adding the newline character by appending the below to my partner list string after N partners

CE=","'\n'

This worked fine when i was using sqlplus directly in the script.

But when i try to pass this partner_list string as parameter to a sql script, it shows '\n' in the query.

This is how i call my sql script and pass the parameter

sqlplus -s ${REFERENCE_DB_USER}/${REFERENCE_DB_PASS}@${DATABASE_INSTANCE} << !!
set serveroutput on size 10000;
set feedback off;
set verify off;
set echo off;
set term off;
set pagesize 0;
SET linesize 1000;
SET TRIMSPOOL ON;

spool  1_del_agreement_spool_$$.lst;

@1_del_agreement.sql ${partner_list};

spool off;

exit;
/
!!

this is my spooled file

>cat 1_del_agreement_spool_18165.lst                                   <

select distinct a.agreement from partner_agreement_map a where a.partner in ('aaa0000',\n'aaa0001','aaa0002','aaa0003',...'aaa0010',\n'aaa0011'...) order by agreement asc
                                                                                    *
ERROR at line 1:
ORA-00907: missing right parenthesis

How can i maintain the newline character when i pass the parameter to the sql script and not have it replaced to '\n'? I have tried ANSI-C quoting but failed.

Please let me know if you would need more details of the shell or sql script