What do you need him to have a mental evaluation for? Custody? Divorce?
I have to be honest with you though that this sounds fairly normal for difficult separations. My husband’s ex left him for another man and still hit the roof when he and I started dating. Threatening me, screaming and yelling at me in front of the children. She also has been diagnosed as being bipolar but would not take the necessary medication because of the possible “side effects”. Has “attempted” suicide and I use that lightly because the attempt was solely for attention.
My own ex dumped me for someone else and then tried to have their marriage annulled until he found out that I would not take him back. Then e-mailed me to tell me that I never really loved him or even knew what that meant. He was angry and hurt and humiliated. He made a mistake letting me go and so he tried every tactic he could to win me back. Separations and divorces are one of the most emotionally stressful things a person can go through, along with a death or loss of a job. There is a wide spectrum of emotions and most people need help in dealing with it.
You can stop the visitations with the stepson but my suggestion is that this needs to be a decision that your stepson is involved with, if he’s old enough…as for calling your son during visits, with him being so young, ask that you can call him once or twice a week at a specified time. Since he is so young there is no way to understand this and talking to you daily while he’s with his father may be confusing him. Just my opinion…