Pictures would have been nice.

You can trace the next out ribs and use that as a guide to making your center rib.  You'll have to "fudge" it bigger..  It doesn't have to be perfect.

You may be able to just glue the fuselage back together, or to glue it together with splints across the weak spots.

When you've got it back to the point where you have a wing and a fuselage waiting to be mated, slide them together then measure from side to side to make sure the wing is centered (I hope it's an equal-span wing!).  Then choose a well-defined spot (like where the spar meets the outermost rib) and measure the diagonal distance from that spot to a well-defined spot in the center of the fuselage (such as the tip of the rudder if it isn't offset, or the tail wheel, etc.).  Squiggle the wing around until those measurements are equal, and double check that the wing is still centered.  Eyeball the wing and elevator to make sure that they're level with one another, or use a machinist's level to make darn sure of it.

Once you know exactly how things match up, then slide the wing out a bit, apply glue, slide it back in, and do all those measurements again (use a slow cure glue).  Then again.  When you've measured all around three times and it looked good each time, then stop fiddling, lock your workshop door, and let the glue dry.