Why do i feel like such a bad person?

Ok to explain things a little better we went to my 7 year old cousins tee ball game here tonight she did really well but thats not what i am trying to state

Anyway we took the baby everyone as usual wanted to see him its a never ending thing when people in my family have babies no one will leave them alone especially not her well it was after her game and she wanted to hold him so i told her to go sit down because in my honest opinion she is too little to be up walking around and holding him especially on concret that just freaks me out im very terrified she is going to drop him because she being 7 doesnt pay very good attention to what she is doing nor does anyone else around her well she still wanted to get up and carry him so my mom told her that she could go over to the grass and carry him not that grass really makes the fall if she was to drop him any better so of coarse i followed her i mean its my son not my moms she thinks just because shes his gramma that she has the last say and that what i say about what i think is best for my kid doesnt matter not to mention it pisses her off to no end when i say something to someone about him again its my kid and i have told her and told her that i do not like my cousin walking around with him let alone on fucking concret! So of coarse she takes him from her and he is really starting to get sleepy and she still wanted to hold him and i told her no and my cousin whom i told no to got mad like she always does so i took him and was going to take him home but then my mom gives me this evil look from me saying that i was taking my kid home that i just ended up leaving him with her because i really didnt want to deal with my mom being all pissy at me for taking my son and leaving which in the end kind of pisses me off at how she treats me when it comes to him yes i appricate her help because she does know more then me when it comes to kids but since im the mom wouldnt i know better for my son then anyone? So should i feel regret or what i really am at a loss on what to do here