To keep or not to keep

It’s a long story, but two months before my wedding I had a falling out with my grandparents after they decided not to come to my wedding to “avoid drama” with other family members who they don’t get along with. However, they sent a nasty email to family members who were going blaming them for the whole ordeal (I know this is vague, but it’s a family feud that’s been going on for years, and even I’m unclear of it’s origin so bear with me).
two weeks after this situation came to light, my grandpa passed away. I went to the funeral to support my mom, but knew moving forward that I still didn’t want a relationship with my grandma because of everything she had done in the past. She’s a narcissist and tries to manipulate people into taking her side and I decided to finally cut her out for good, but I never confronted her (or my grandpa) about why I was upset.
My wedding was last weekend and it was absolutely beautiful and perfect. 💕 but the day we got home there was a card in the mail from her with a check for a decent amount and a letter saying how much she misses talking to me and wants to hear all about the wedding. She literally has no idea. I’m tempted to just “return to sender” the card and leave it at that. And even though I can take it or leave it with the money, I thought of just cashing it and still avoiding contact with her, but that doesn’t feel right. I’m at the point where I probably need to confront her about why I’m upset, why I haven’t contacted her since I saw her at the funeral, and why I’m not keeping her money. But idk how to go about it. I hate confrontation and this whole situation has been hard on my mom. My parents helped with a lot of the wedding so I avoided confronting my grandma before it because I didn’t want to rock the boat there. But now I feel like something has to happen. Any advice or input? Thanks!