1997 Mazda 626

Engine Performance problem
1997 Mazda 626 Automatic

Hello.I have a mazda 97' 626. Its currently out of commission right now.I havent drove it in a while since the last time it overheated and gave out on me. It had been giving me problems.I had to replace a bunch of belts n change out the whole power steering pump. In the midst of that, the mechanic told me I had a blown gasket n I should get this sealent called Blue somethin-or-nother. Anyway, I got it but it did nothing and he said I'd have to gt the gasket replaced. The car overheats and when I lift up the hood theres this white stuff squirted all over the engine. Looks like someone lifted the hood and splashed a can of white paint.I just wanna know if its the head gasket before I shell out all that money to fix it.I may just get rid of the car and bus it till I can get a new one. Rather not tho.I only had it for like a year.