Your opinion

So I get a phone call this morning from my very upset mother. Apparently the man that owns the place we board our horses called and lambasted her for 30 minutes last night. He was mad that I had put one of the other borders on my shoeing schedule. (at her request thank you very much) Well I guess he thought he was going to shoe her horse and hadn't told anyone. I didn't think anything of it when she commented last week that her horse needed shoes. Always looking to be helpful I asked if she wanted my guy to do it. She said yes. No big whoop. Well then Mr. Cranky pants (the barn owner) said I am taking money out of his pocket and went on to tell my mom that her horse is tearing his barn down and that it was gona cost her 2000$ to fix it and that my shoer was crappy and our horses weren't exercised properly. He even went so low as to attack her personally.
I could not believe it. This is someone that I thought of as a friend. If I thought he was going to shoe that stupid horse I wouldn't have offered up my shoer. Also when Moms horse kicked out the first board in the shoddily built barn, she offered to help fix it with his help, being that she didn't have the know how or the tools to do such a job herself. Cranky pants never got around to helping her. (a common trait for him) Now the hole is huge and he wants her to pay for it. She is so upset that she wants to move. (OK I understand that) What do you all think? Would you make her pay for it. How would you deal with this situation? Keep in mind that we have been with this barn for 7 or 8 years. Many of those years we were the only ones there. Sometimes board is late(never more then a week) but we always pay it. I am really at a loss here.