Hello Cote, sorry to hear about your strain 
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Dare I say such an obvious thing, but even after two months, I'd definitely be guided by your body, if I were you - if there's still pain or more than mild discomfort then I'd continue to be vigilent.
The groin area has a series of 'insertions' - tendons - that feed up from the legs into the lower back - and they can take many months to heal if damaged. Also, it sounds like you will have scar tissue that needs to re-align. That remodelling process can involve some pain as part of that process, so the pain itself may not be due to more damage, but rather as a consequence of remodelling.
Maybe consider very light stretching of the injury at home, in preparation to your return to yoga. Eg - you could try a kitchen chair back, to hold onto for support, so you don't put your whole weight onto the injury. Try things like side-on stretches very gently, then forward/backward to counter-stretch - then have a warm shower or bath after to ease off.) Then see how you feel 24 hours later, that's when you will know how well it is healing.
I would suggest:
- steer clear of wide-leg stances like triangle or warrier for a further month/6 weeks at least, as they can be very strong, can't they.
- try sitting cobbler or lying butterfly, as these are non-weight bearing and you can control the degree of stretch - they will help to gently restretch the injury. A belt is good for support.
Maybe aim for a 1 weekly class for a month - then if you feel you are ready to increase, slowly slowly does it! I tend to be an ayenga / hatha fan rather than ashtanga, some of the deeper stretches I found needed at least 48 hours for the body to recover. Also I found the ashtanga class at my gym got rather competitive (groups of men using it as a workout!) so I now stick to my village hall classes which pretty tame by comparison lol.
Hope you get back to your class soon.