Ok, I think I have a solution for this new crashing problem - somehow, the problem seems to be in messages and syncing old messages with this new Viber update. At first I just reinstalled Viber on my phone, and this didn't help. Then I did a soft reset- that didn't work also. I tried clearing the app cache - also without success.
So, at the end, I deleted all my conversations on/via Viber desktop, all the groups, and all history, and then reinstalled Viber on my phone. After installing again, I immedeately went to Viber/Settings/messages/ and cleared all message history.... Started new conversations, friends re-invited me in groups again, and since then, I didn't experience any crashing...
Hope this helps a little.