Squats are a very effective workout that gets your whole body involved in the right proportions. The key to keeping your adductors involved is to push your knees apart when you are "in the hole" and while you are raising back up. The squat gets your calves, hamstrings, glutes, quads, adductors, core, and back muscles all together in the right proportions.
Word of advice: swallow your pride and go light at the beginning. As long as you add weight every session for as long as you can do that, you will be lifting heavy weights soon enough.
The primary reason for muscle injuries is unbalanced strength. This is why I recommend a compound lift like the squat (to parallel) to build up your adductor (groin) muscles. There will be a number of other supporter/stabilizing muscles that need to catch up, and it's always the weakest link that gets injured first.