Diastasis Recti

Anyone know what i can do to help my diastasis recti? I really didn’t know much about this before I had my baby 4 months ago. I’ve been going to the gym but only doing cardio so far and not noticing a huge improvement in my stomach fat :( I’m pretty sure it has a lot to do with the ab separation. I hear you can’t even do sit ups or it makes it worse. I’m not sure what exercises to do to help tone my stomach.