SOS (つ╥﹏╥)つ

Okay, so i know this is my first 'blog entry' but i desperately need some advice if anyone is willing to help me out here... 

So i have a really close friend in school that i sit with in classes and hang out with during breaks, but recently they have been constantly making me feel like whenever they get upset the reason is my fault when i usually have no idea how it could've been my fault since i didn't do anything. For context, they have struggled for a while with mental health and i've heard a lot about past mistakes they've made that ended up making them look really bad (they basically just victimized themself and blamed the other person for hating them when they were the one in the wrong). So obviously knowing this, i have been cautious enough to try and understand them and let them know i am always there if they need and i think i have made it clear i'm willing to forgive and let go of times they've hurt me because its literally just not in me to be able to hold a grudge.

For several weeks though, they've been making me second guess my willingness to be friends because the amount of times i've ended up having to apologize when they are clearly in the wrong has made me feel like i'm just letting them get what they want and not giving a damn when it really is the opposite and irritates me extremely. 

My problem here is pretty clear but the main reason i'm asking for some advice is because on the inside i want to just forget all the times they've been mean to me and keep being close, but deep down i feel trapped in this relationship and i think it would feel really relieving to let go and live my life not worrying about how i might hurt them on accident. In my mind a true friend wouldn't feel hurt about me accidentally ignoring them or talking to other friends. Please someone help meeee!? 

Should i keep being friends with them and push through the daily struggle of interacting with them in school or should i let go of this friendship somehow???

Also, just a side note but i'm still working on my profile so please don't judge--it's taking foreverrrr ᯓᡣ𐭩