1995 Volvo 960 Engine does not turn over

Problem began maybe coincidentally when my brother borrowed my battery for a day and when he returned it my car idles erratically and even died out a few times but since then it could not hold idle smoothly. Thinking that it was spark plugs I replaced them and during initial drive thought I had fixed the problem when rough idle came back the symptoms I felt was inadequate fuel causing hesitation so I gave it a bottle of fuel injector cleaner. Again in the beginning it felt as if this might have solved the problem but again like before as I drove the car the rough idle came back and I felt the car starting to lose power on inclines and from the line. I noticed fuel leaking from the fuel intake manifold cover (I believe it is) and continued to drive it when all of a sudden the car would not start up. It would crank but not allow itself to turnover.I sprayed some starting fluid into the air intake but it attempted to turnover but as I press the gas no pressure was present and the engine just died. My car is now stuck and I don't really know what to do next! Can somebody out there please help!