hi HK

Just rest for now. That's the key thing. You don't want to strength too much, because the muscle is already torn and so if you stretch too much, you just pull even more and make it worse.

Having said that, you don't want it to heal inflexible, so you need to keep some flexibility - just avoid pain, that's all. Try to avoid sitting in a 'scrunched up' position for too long, stretch it out gently. It will take a couple of weeks, depending how bad it is, and then you start gradual strength.

You can keep going on the upper body stuff - again, just avoid pain. The strength work you do when you return must also be very easy, mild stuff, like light weight curls, lunges etc - nothing explosive. IT's the speed of movement that will re-injure it, so just take it easy and let your body tell you!