I use to be like this but I learn the hard way, people you are trying to help sometimes will just take you for a fool. I still show kindness and helping hands to people a lot of time but not at the detriment of myself anymore.
Don't be too hard on yourself just take it slow, you will get there.
Yeah, it's good to understand when to and when not to. People sometimes believe we have and that's why we give and not like it's a sacrifice