Another chance

My father wasn't the best father I can count on one hand how many times I seen him growing up. I might have heard from him but that was also few and far in between and only calls filled with broken promises. I hadn't heard from him in years until I was about 20 and thats because my uncle his brother kept pushing me to call him. (Im not really close to them and don't know them either but I felt like they was putting in more effort). Anyway Im 27 now we have talked on and off since I was 21. When I got pregnant my uncle's who are my friends on fb told him. He wants to be an active grandfather in my sons life. I will say he has sent him some clothes and blankets. My son is 3 months and im just not sure. I still really don't know him or his family. I know who they are but thats about it. My grandparents use to come around when I was younger but after my grandma died that was the end of that. I don't hear from my grandfather either. I sent him a card after his second wife died a couple years ago trying to at least get things rolling. I got nothing. I heard he felt like I just wanted money. (He is well off) My mom nor have I or my brother ever as them including my dad for anything. All she ever wanted was for them to be who they are me and my brothers family but she said she wasn't going to beg. About 4 years ago me and my dad got in a huge argument because he tried to blaim my mom. But I was smart as a child I know she gave him chance after chance to be in our life. She paid for him to go on a couple trips with us one he didn't even show up for. Plus just like he took her to court to drop/lower his child support he could of took her to court if she really wasn't letting him see us. And we have another brother by a different women was it her fault to? He wasn't in his life either. Im looking for advice, should i let them in. My mom would definitely not be happy thats a whole nother issue after trying for years she now just don't want us to have anything to do with him. She said your grown now its no point. He wants me and my boyfriend and our son to go California to visit him and his family. My boyfriend wants to give it a try because he is a family person but i don't see them as family really and i don't want my son hurt in the long run. I always said when my child started asking questions like where is grandpa I was going to just say he went away a long time ago or he died. Advice please