Node proxy requests from many users to other rest services

Question

I'm trying to write a single backend that proxy request to many products in our internal network (intranet, bpm etc...). In the case of the bpm Bonita I need that every user login with his own credentials to the service that responde with a cookie. My idea was to save the cookie for every user after the login in the database then append it to every calls made by users.

The function:

        let unirest = require('unirest');
    //I try to call  it with the cookie of the last session passed in data.cookie
    unirest.post('https://bonitaurl:8443/bonita/' + data.query)
        .headers({
            'Accept': 'application/json',
            'Content-Type': 'application/json',
            'ContentType': 'application/json'
        })
        .send(data.Presult.params)
        .jar(data.cookie)//import cookie from database
        .strictSSL(false)
        .end(function (Tryresponse) {
            if (Tryresponse.statusCode != 401 && Tryresponse.statusCode != 404) {
                console.log('loggedin as : ', data.user);
                console.log(data.cookie);
                console.log(Tryresponse.statusCode);
                return callback(Tryresponse);
            }
            else if (Tryresponse.statusCode == 401 || Tryresponse.statusCode == 403) {
                console.log(Refresh cookie for user : ', data.user);
                request = unirest.post('https://bonitaurl:8443/bonita/loginservice')
                    .send({'redirect': false, 'username': data.user, 'password': data.pass})
                    .headers({
                        'Accept': 'application/json',
                        'Accept': 'application/x-www-form-urlencoded',
                        'Content-Type': 'application/x-www-form-urlencoded'
                    })
                    .strictSSL(false)
                    .jar(true)//save cookies
                    .end(function (loginresponse) {
                        if (loginresponse) {
                            //Call using previus cookies

                            // Start DB
                            let pgp = require("pg-promise")();
                            let db = pgp("postgres://DBUSER:*****@localhost:5432/MYDB");

                            //I will save tokens to database
                            db.none("update users set bpmtk = $1 where username = $2  ", [JSON.stringify(loginresponse.cookies), data.user])
                                .then(function () {
                                    console.log('updated ' + user);
                                    unirest.post('https://bonitaurl:8443/bonita/' + data.query)
                                        .headers({
                                            'Accept': 'application/json',
                                            'Content-Type': 'application/json',
                                            'ContentType': 'application/json'
                                        })
                                        .send(data.Presult.params)
                                        .jar(loginresponse.cookies)//Import cookies from the last request
                                        .strictSSL(false)
                                        .end(function (Proxyresponse) {
                                            if (Proxyresponse) {
                                                return callback(Proxyresponse);
                                            }
                                        })
                                });
                        }
                    })
            }
            else {
                console.log('Error code: : ', Tryresponse.statusCode);
                return callback(Tryresponse.statusCode);
            }
        })

The code works and every users can login correctly with the last cookie but if I check the session of the user it points to the last user logged in! To avoid this I have to login , execute calls then logout every times! this is very bad for performance. Any Idea ?