Hi MonkeDonke69,
We're glad you've reached out in Apple Support Communities, we'll be happy to help out. You do not have to create a new Apple ID for your iPhone to work. You should still be able to get to your Home Screen and if needed, clear up storage. Second, since your current iCloud password isn't working, try resetting the password.
First, you want to gain access back to you Apple ID. If you forgot your Apple ID password has several different methods you can use to reset your Apple ID.
One step you can try if you have the Apple Support app download, you can follow these steps. Instead of asking a friend, you can use your iPhone since it has a different Apple ID.
Use the Apple Support app
Ask your friend or family member to open the App Store and download the Apple Support app on their iPhone, iPad, or iPod touch. Can't download the Apple Support app?
Then open the Apple Support app and follow these steps:
1. Tap Passwords & Security.
2. Tap Reset Apple ID password.
3. Tap Get Started, then tap "A different Apple ID."
4. Enter the Apple ID that you need to reset the password for.
5. Tap Next, then follow the steps on your screen until you receive confirmation that your Apple ID password is changed.
If you can't change or reset your password
If you tried the previous steps and were unable to change or reset your password, try these steps instead.
1. Go to iforgot.apple.com.
2. Enter your Apple ID. Did you forget your Apple ID?
3. Select the option to reset your password, then choose Continue.
4. Choose to answer your security questions, get an email, or enter your Recovery Key.* Learn what to do if you don't receive your verification or reset email.
5. Follow the onscreen steps to reset your password.
After you reset your password, you'll be asked to sign in again with your new password. You also might need to update your password in Settings on your devices.
Once you have your Apple ID password reset, verify you have access by going to iCloud using a web browser.
To erase the iPhone, follow the steps found in Erase iPhone. It's important, if you have added any new data to this Apple ID you are currently using, it will be erased when you sign back in with your original Apple ID.
Wipe all content and settings from iPhone
1. Go to Settings 
> General > Transfer or Reset iPhone.
If you’re erasing your iPhone because you’re replacing it with a new iPhone that you have on hand, you can use extra free storage in iCloud to move your apps and data to the new device. Tap Get Started, follow the onscreen instructions, then return to Settings > General > Transfer or Reset iPhone.
2. Tap Erase All Content and Settings.
3. When iPhone restarts with all content and settings erased, you have the option to set up iPhone as new or restore it from a backup. See Turn on and set up iPhone.
You should be able to set up your iPhone using your original Apple ID. As for the storage, this is a good link for how to free up storage. If you need more space for an update on your iPhone, iPad, or iPod touch.
Good luck!
