*Needs answer quick* question about fake steam site login scam

So I put my credentials in a fake steam website and lost a big item, I changed my password, are the scammers still in my account? what do I do?

Never insert your Steam credential in sites that haven't, near the URL, written in green "Valve Corp. [US]".

Usually when you change passwords, other sessions cannot continue to utilize the account. You can visit this url while logged in via web browser: https://store.steampowered.com/twofactor/manage and click the "Deauthorize all other devices" button or reach the same page by clicking Steam in the upper left corner of the client and going to settings and manage steam guard account security and click the same button mentioned above.

If they got a hold of the shared secret and the above does not alter the activity, disable mobile auth and re-enable it for the shared secret to change.
You should also consider changing your other online accounts passwords you may have used the same password for.

And for the last recommendation do not use item sites, they are not made to help people get what they wish usually, especially gambling. They are made to profit.