MIL naming my child??

So my husband and I have had a really hard time naming our son and he wanted to name him after his step dad who died when he was younger. I wasn't a huge fan of the name and I felt bad because his stepdad meant so much to him. We finally agreed on the middle name Allen and that's the name I posted on Facebook when he was born. The next week my MIL cornered me and asked me why we didn't name our son after the stepdad and said my husband had called her and told her we were giving him the middle name "Alan" after his stepdad. I was shocked. I had no idea that his step dads middle name was Alan and I had no idea that we were apparently naming our son after him. She said she started bawling when she found out the name was spelled Allen instead of Alan. I feel so manipulated by my husband that he didn't tell me Alan was his stepdads middle name. I obviously like the name since we chose Allen and I would have loved to use a name that means so much to him. We spelled the name Alan on our son's birth certificate, but now my MIL wants proof and a copy of the certificate to make sure I spelled it Alan and not Allen. I'm just mad and feel like she's the one forcing me to spell the name that way now. Should I keep the peace and just send her a picture or ignore all her crazy texts about it?