I was at the Edric fight and since I struggled solo I joined an online session cause 2 is better than 1.
However that person had finished the fight and as I joined finished Act 1 before I could do anything and that triggered the ending for me aswell.
This really annoys me cause now I missed part of the story, missed out on loot (sure I'll get better down the road) and feel like I cheated my past what was an exciting challenge.
It really shouldn't happen that I join a session that is further ahead of me, I don't mind having to redo a bit when joining one.
Is there a way to get back to act 1 without make a new character and playing it all again?

Thx in advance