How to inform the user they have been logged out from their previous account when logging in to a new account in a new tab

We have multiple products that belong together, a suite of products. They all share a single-sign-on solution ie users can log in to one of the products and are automatically logged in to all of the other products they might have access too. Users can only be logged in to one account at a time ie if they have an active session and go to any of the products log in pages they are automatically re-directed to the products dashboards.

Users can be invited to use these products. Upon invitation, they have to create an account. As soon as they create their account they are logged in to the product. The flow is like this:

User receives invitation email > User clicks accept invitation > User sees a create account screen in their browser > User enters their name and password and clicks "create profile" > The user is logged in to the product.

Now, imagine a user has an account and is logged in using email-1. They now receive an invitation for email-2. They accept the invitation. The create profile view is opened in a new tab in their browser. When they click "create profile" they are logged in to the product with email-2. Their previous login for email-1 is ended and they are automatically logged out from that account.

What should the user see when they go to that tab? What is a good message?

We're thinking a modal with a message saying they have been logged out due to the fact they logged in with a new account. They will also get two options: 1) Continue with email-2. This basically refreshes the window, close the modal and they are now in their email-2 account. 2) Log back in with email-1. This logs them out from all accounts and they are taken to the product login view. In this case if the user goes to their second tab they see the same modal and message but for the other account.

Thoughts?