I understand your concern, the behavior of people do affect. But there is a saying, "there are only two ways to live your life, let things happen the way they happen or take responsibility to change it". Point is, why expecting from people that they would be nice in the first place at all? You go with an approach to satisfy your own need rather than satisfying other people's need. Deceiving, backstabbing is nature of human, just assume it and then make your strategy or approach. You cannot trust people online easily though irrespective of the fact however sweet they present themselves. Sometimes you wont get platter at hand, you need to get up and prepare one for yourself. You cant stop living your life fully just because there are people who deceive you. (like you cant stop boarding pubic transport just for the fear of pickpocket)
Love yourself, be mean, you start to take advantage rather than people take advantage of you. If you are worried to confront, go to gym or boxing center ask people to confront you at once so you lose fear of being confronted. Try try and satisfied that you tried rather than being alone or dying in seclusion. I am not a pro lifer not an advocate of S, but one should exhaust all options, live and die with dignity.
On a very personal note, I've been deceived and backstabbed from everyone including people who I help stand up and be something in life. It didnt affected me. But then there was someone so dear who backstabbed and it affected me and today I lost everything. I've realized I exhausted all options and very very bad health condition as a result. Why I landed in this situation, coz it was my mistake I trusted someone knowing of human nature that looking at money it changes. I can blame others but then its not going to solve the problem at hand. Shit happens, mistakes do happen. All i have at hand is sufferings and learning.