happiness is against me

This year has probably been the worst year of my life.
I have suffered from anxiety since i was little, and i dont remember a time without it.
however, disregarding that, i feel like no matter how much i try to be happy, happiness turns against me, or life or the universe.
the beginning of this year was great, i had great friends, a loving boy friend, a loving family.
then after coming back from a (what i though was a) perfect holiday with my then boyfriend in june everything just turnt to crap, it has been a downward spiral.
My grandad fell ill and was in pain for about a month before he passed away 3 days before my 19th birthday, and i was heartbroken. My grandad was the funniest, if not most cautious, protective loving man i knew. Although he was very old and in a lot of pain it was still a massive shock to the system to not have my idol around anymore.
however, i started to deal with the loss and started to heal again, knowing he was in aplace without pain and suffering.
Then, i went on holiday with my so called best friends and it was a disaster, and something that was meant to cheer me up put me into an even more insecure and weak state.
when i came home i had to wait about 3 days for my boy friend to come home from his holiday. when he came home everything seemed to be fine until the next day he wanted some ‘space’. later that week he broke up with me, which was completley out of nowhere, becasue for all i knew he ‘misssed me so much’ while he was away. which was another situation where my heart was left completley broken beyond repair ( i had been going out with him for a long time and he was my best friend).
I had a mental breakdown, i couldnt cope with the stress of losing my grandad and my boyfriend leaving me and with the stress of going to university later that year, my body couldnt cope, and with the underlying condition of anxiety and depression everything was heightened.
My mum took me to see a doctor, and i have been giving sleeping tablets (After not getting a natural nights sleep since june) and was put on an anxiety pathway to help.
I did start to feel a little better after about a month. i still cry nearly everyday and i miss my grandad and my ex, however things were looking up. i had my friends and my family and my dog, who would always be there to cuddle and listen when i cried.
then my dog started to become ill. and now she is in the vets, and we dont know if shes going to make it or not. shes 14 years old and shes in constant pain. my parents have warned me that she might not make it through this, and this is the last straw.
Everytime i begin to even start to repair my heart and learn to laugh again, something out there decides that life wasnt hard enough already. and to top it all off i feel so alone because my friends are always ‘too busy’ to make time to see me, when all i need is just a friend. i have my family, but i dont want them to see me hurt anymore, ive put them through too much already to do this again.
i feel like the only way im going to heal my shattered unrepairable heart is by not being here anymore. but im too much of a coward to do it.
but i just dont want to feel the pain anymore, and i dont want to try to be happy again because if its anything like the past year another bad thing is going to happen to kick me down again.
potentailly loosing my dog is the last straw. i cant remeber a time without her. and she has been my rock through the past couple of months.
i cant live like this anymore. i cant carry anymore pain around with me. i feel like happiness is against me, it doesn’t want to be felt.