Who should I believe? Idk what to trust

So here’s a backstory so you can understand more: I am in an interracial relationship. My family was/is strongly against it and would say and do hurtful things to try and break us up. My mom in particular would say things to make me upset with him before our dates. She also has memory problems and gets confused often.

So last month my mom was working at Walmart and said she saw my bf there. Fast forward past the holidays and I’m about to go on a date with him. Right before I leave my mom asked if he mention “Jessica” cause he was with a girl at Walmart. She said they were there buying household type things.

I asked him “so how is Jessica?” He looked at me so shocked and confused and asked who I heard that name from. Then he explained he ran into our friend and was shopping with her, and doesn’t know a Jessica ever. His explanation was quite believable to me and made sense.

Then when I got home and talked about it with my mom and she swears she heard the name “Jessica,” and would never lie to me.

When i mentioned it to him again he got super defensive and said he is telling me the truth and would never hurt me.

I want to believe both of them because ik both of them care about me. My mom has a history of hating on him as well as not understanding what people say. I also wonder why she would get so many details wrong. Then my bf was getting defensive when I asked him about it again.

Advice?