Hi C and welcome, well done on looking for help.
Read the othe stories here, you will see a lot of stories similar to your own. You will also read the succes stories, what are they doing that you can apply to your own situation?
As Stilltime says, get some barriers in place. You can get a blocker for your PC which will stop those online sites. Who could help you with financial accountability as well?
It is an addiction, you introduce yourself as a gambler. Maybe check out the 20 questions on the Gamblers Anonymnous website and you might change that to compulsive gambler, there is a big difference.
Keep posting and let us know what positive steps you are taking to help you avoid your next bet.