Is talking to a Non-Muslim opposite gender haram?

We knew each other from social media and we have been talking for years.. A few males and a few females.. (im a female) **Expect one male, all others are muslims..** and its noted that now when i talk to them, i dont feel happy anymore.. like it causes me stress.. but i also dont want to stay apart from them.. however when i leave, it gives me a peace of mind. **What do u think i should do?** And when i talk to them.. My imaan becomes weak :( tho i still havent figured out why.. and there is always debates going on with the muslim friends and non muslim friend about why he should become a muslim.. tho they insult each other while they are at it.. and he debates why they should not trust on the religion.. its been stressful These days I have been getting more interested in Islam Alhamdhu'lilah and because of a post i saw that says we shouldnt talk to opposite genders.. I cutted my contact with them.. but i feel bad.. **so i dont really know what to do..** **Is talking to them Haram?** we treat each other as Family..like brothers and sisters and we know each other's all the secrets and thoughts.. so on.. **So what do you think i should do in this situation?** wasalaam Alaikum Wa'rahumathaullah Wa barakaath