I'm depressed, i've been through a lot more than your average 22 year old, and i don't know what to do?

I've been through a roller coaster ride this past month has been very difficult, I'm a heart transplant patient, have had heart failure with the transplanted heart, and of course day to day problems. But this past month has been extremely difficult, since september i've been sick again with my heart, november i had procedures done infusion treatments done. with all that going on my boyfriend in october said he needed a break because he couldn't take the arguing, and we eventually got us back in order but the fighting just continued and got worse since being sick and getting sicker. I have my bad days and my good days but its all so emotional and he doesn't think its fair to him the way he's treated but i don't know? So getting to march he broke up with me the end of February and that week my heart went into a fib, and needed another open heart surgery proceudre. once i told him on his normal 3:30 phone call i was in the ICU he didn't think it was that serious!! and weve been texting this month mainly me trying to get answers cause there's a chance i could go. as he's been being "nice" but not being fair to me, i just can't get over some of his antics and he can't seem to understand i've been sick this whole time and its emotional and i know that its wrong to take it out on him but theres so much. I just started citalopram and i know it takes a while to kick in but i feel that it may not work, i would love advice, guidance, and i know it sounds so petty to be concerned about a boy while your life is at stake, but believe me its everything from the heart, to the normal break-up feelings which i might be taking them a bit harder, with life itself.