You should ask yourself why are you holding bitcoins in the first place. Short term gains? You don't want the feeling of missing out if it ever hits say $10k range? You just like the concept of it and want to be a part of it?
I'm not going to tell you what to do, but just few things to consider:

• you can only lose 100% of what you invested. Potential gains are uncapped.
• every issue (blocksize war) gets resolved eventually. It's not always pretty and can take a very long time, but it will happen.
• there's more options than just hold or sell. You can sell half and hold the rest. You can divesify/hedge against other altcoins. You can do any combination you want (cash out 30%, buy ETH with 30%, hold the rest etc)
• keep the cool head when making any decisions. Panic buyers/sellers tend to get burned