python telegram bot, "socket.error: [Errno 98] Address already in use" - nginx

Question

Im developing a telegram bot with this api and I tried to use its webhook example to set up my own bot with webhook method.
I have an Ubuntu server and I have set up nginx on it.
now when trying to run my python bot, I get this error:
Traceback (most recent call last):
File "bot.py", line 106, in <module>
router.run(host=WEBHOOK_LISTEN, port=int(WEBHOOK_PORT), ssl_context= (WEBHOOK_SSL_CERT, WEBHOOK_PRIV_CERT), debug=True)
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 841, in run
run_simple(host, port, self, **options)
File "/usr/local/lib/python2.7/dist-packages/werkzeug/serving.py", line 720, in run_simple
s.bind((hostname, port))
File "/usr/lib/python2.7/socket.py", line 228, in meth
return getattr(self._sock,name)(*args)
socket.error: [Errno 98] Address already in use
so I checked what is using my port 443 and the process is nginx:
root 30734 1 0 Aug21 ? 00:00:00 nginx: master process /usr/sbin/nginx -g daemon on; master_process on;
I can't turn off nginx because my website is on it, and I need the port to set up telegram bot.
EDIT: I will put my code here for more clarification:
WEBHOOK_HOST = 'mywebsite.com'
WEBHOOK_PORT = '8443'
WEBHOOK_LISTEN = '0.0.0.0'
WEBHOOK_SSL_CERT = "/etc/letsencrypt/live/mywebsite.com/cert.pem"
WEBHOOK_PRIV_CERT = "/etc/letsencrypt/live/mywebsite.com/privkey.pem"
WEBHOOK_URL_BASE = "https://%s:%s" % (WEBHOOK_HOST, WEBHOOK_PORT)
WEBHOOK_URL_PATH = "/%s/" % (TOKEN.get_token())
router = flask.Flask(__name__)
#router.route('/', methods=['GET', 'HEAD'])
def index():
return 'OK'
#router.route(WEBHOOK_URL_PATH, methods=['POST'])
def webhook():
if flask.request.headers.get('content-type') == 'application/json':
json_string = flask.request.json
print json_string["message"]["text"] # here I get the text of message
return ''
else:
flask.abort(403)
bot.remove_webhook()
time.sleep(3)
bot.set_webhook(url=WEBHOOK_URL_BASE+WEBHOOK_URL_PATH,certificate=open(WEBHOOK_SSL_CERT, 'r'))
router.run(host=WEBHOOK_LISTEN, port=int(WEBHOOK_PORT), ssl_context=(WEBHOOK_SSL_CERT, WEBHOOK_PRIV_CERT), debug=True)