I’m so glad you wrote. You’re absolutely correct. Your jealousy is likely to cause the very thing you fear — the dissolution of your marriage. Neither you nor your husband can live with this level of distrust in your relationship for very much longer.
I’m very glad you started seeing a therapist. Do stick with it. The therapist who is getting to know you will be much more help to you than I can be. Ask her if some medication might be helpful. There are medications that can help settle the symptoms of OCD. She may recommend a combination of talk therapy as well as a medication trial. Do consider it.
I do suggest that you talk to your therapist about bringing your husband in with you now and then to reassure him that you are working on the problem. He may also be able to give the therapist some important information about your behavior that you may not see or understand. That will help move your treatment forward more quickly.
I wish you well.