Try to move to a safe space and only tell people you trust about your new address.
Buy a new SIM card and only give the number to people you trust. Change the passwords to all your social media accounts (e-mail, Facebook, Instagram, etc.) to make sure you are not followed.
Cancel old bank accounts and credit cards, especially if you shared them with the perpetrator. Change your bank when opening new accounts.
If you stay in the same area as the perpetrator, change your daily routine. Take another route to work, avoid places where you used to go together and he could find you, shop in different stores/markets. Always have a charged phone with you, in case you have to call 112.
Ask for help from people or organizations specialized in the topic of violence. Find a support group. Try to understand what this new life means for you.