Old friend occasionally messages me.

Hi, I don't use Reddit much and dont even know if this is the right subreddit for this but an old friend of mine (both 19m) will message me every couple weeks/months, trying to catch up with me and make plans. We were eachothers first friend in kindergarten but ever since middle school our personalities differ too much for me to actually enjoy hanging out with him or texting him. He is pretty socially awkward and I know that I'm probably one of the few people hes comfortable talking with and can call a friend, so I try to be nice, text him for a half hour at a time catch up and then forget about it, because I know it means a lot to him and takes no effort from me. I just feel like the facade I put up isn't good for either of us but I dont really have the heart to ignore him or tell him all of this. I'm aware this all probably sounds very mean but I dont care, any advice at all will help, Thanks.