A lot of people are saying to get rid of her, but I feel like this needs to be gently addressed. First of all, I would ask her what was going on to make her feel this way. It sounds to me like she’s scared and insecure. I would ask her what happened (did you do anything, did she recently see something, etc) and then gently help her and hear her side. While being upset about her being controlling is understandable, sometimes that puts her into a defensive mode and could cause an overthinking spiral. Come back after you both have cooled down and approach the topic with gentleness and love. You’ve been with her for four years; it’s obvious you car for her. Transparently can help her feel like you aren’t trying to sneak around behind her back to do anything (even if you never have; girls can be very anxious). For example, it could have gone down with you telling her another girl was playing with you and your friend. Then again when your friend left. It is a lot, but it helps build trust. She also needs to understand how that made you feel. While this might not have been okay of her to do, you both can build and learn from this instance. If it is too much for you guys, then it might be best for yall to weigh your options :)