M/C last month sister inlaw pregnant with same due date

So after two miscarriages. The most recent just happening last month. I found out this weekend that my sister inlaw is pregnant And due the week before I would have been due. We didn't even know we were both trying. I was strong after my miscarriage and just tried to pick myself up and dust it off. But after finding this out it has thrown me over the edge. I truly want to be happy for them but I have so much resentment and I can't help it. I just know every time I see her it will be a constant reminder of how pregnant I would have been. And it will probably hit me again when she has the baby. I feel terrible for having these feelings. But it didn't help the situation that my sister inlaw wasn't very sumpathetic about what had happend to me. Has anyone Elese gone through anything similar? How did you feel?