Dreading this weekend.

We are spending the weekend with my parters family who lives 4 hours of driving away and I usually love doing that but I lost my baby 6 weeks ago when I was 20 week pregnant. And that still hurts so much. 
While there we will meet my sister in law who is also over 40 and got pregnant a little after me and she is now 20 weeks pregnant. We had both been trying for 1.5-2 years before getting pregnant and I am very happy for her but at the same time seeing her will be so hard. 
I feel guilty for failing to give my partner the child he wanted for so long. He had given up having any children of his own until we got pregnant and now he most likely never will. His mother has asked about grandchildren his whole adult life and for him it always felt like a failure that he didn't have any. 
I fear I will cry the whole weekend without having any real way of getting  away from everything.