I once had a 55gal s/w tank bust a seem with no warning at all! cheap azz tanks! But anyway after that I don't take ANY chances with cracks , I would start thinking about a new tank
Just to be safe, Think of it this way ,the cost of that tank breaking and the damage it would do is ALLOT more then the cost of a new tank
I am soooo sorry for you , that really sucks. Whatever you do I hope for the best for you