Insecurities + trust = relationship or no relationship?

I'm in a relationship, it's been just over a year and throughout the time we've been together I've found out that they've been talking to other people, I know who the people are, but they deny it and I've seen actual evidence of it! I'm too scared to end it because I don't want to be on my own and I love them to pieces hence why I'm still with them; but it's making me so unhappy, makes me cry and I feel so insecure.. they've promised not to do it again but I don't know if I will ever be able to fully trust them again.. just don't know what to do anymore! I can't help but think they're talking to people the whole time, meeting up with others because every time I ask to see them they say 'somethings come up' or 'sorry, I'm busy' please help :/....

If they're denying it and you've seen actual proof, you shouldn't be with them. Loving someone and letting them go is hard, I understand. But if you're unhappy, it's not worth you. You have to think of yourself before you can think of others. If you're unhappy you can't make someone else happy. They lied and tried to hide things before, and make up excuses to not see you when you should be the most important thing to them. They should be ecstatic to see you whenever possible. No relationship is worth being unhappy and miserable in. Even if you love them. You don't deserve it.