You need to set boundaries and stick to them. You are the only person who can decide those boundaries. It's hard, I had to the same with my dad. Just tell him, tell him again, and if he breaks your boundaries, then tell him you must back off a spell (I ended up having to do just that and it saved my sanity!). You have to look out for yourself, any kids you have and your DH first, then you can worry about other family members. The only way anyone can guilt you into anything is if you let them! Good luck, I've been there, done that!