I’m so sorry to hear about your dad passing away before you could try to build a relationship with him, as well as your mother-in-law also dying. It is sad to hear that your mum prevented you from getting to know your dad, and it’s natural that you are grieving for him and for what might have been.
I’m glad that you’ve found this online community and I hope it helps to have this space to share your emotions honestly. Here are some other posts by people who lost their fathers that they didn’t know well - these are slightly older posts, but it might help you to read what other people’s experiences were:
Rae posted: Dad is gone
@DN61 posted: My Dad
If there’s anything I can help with or you have any questions about using the site, you can contact me at online.community@sueryer.org.