Stoneheather I feel I am NAGGING YOU TO DEATH
Ask yourself? Will seeing this man help me keep my blood pressure down? Go home on the sick!
If you must stay then tell him about how great it is you got back with your bf and how happy you both are that you got pregnant straight away. You're sure the baby is Greg's, you just have to find a way of letting him know that.
Plan A (avoidance) is better.